I have a tenure-track assistant professor interview coming up. I am proposing a monograph and wanted to include a visual to go with it. Is it too much to include a fake book cover to show interest/determination? Or do you think it would look good?
In your question, you say that you are "proposing" a monograph. This suggests that you don't actually have a contract signed with a publisher yet. If that is the case, I think it is a little bit dangerous to prepare a cover by yourself.
The people who review your application want to see concrete results, achievements that have already taken place. If you already have a book contract signed, then at least the faculty can understand that there is a very strong likelihood of the book getting published, and therefore that is still acceptable for them.
But, if you present a fake cover for a book that you are still planning to propose in the future, this might give a misleading impression that the publication of your book is already fully decided. And if the reviewers realize after doing a closer examination that in fact you don't have a contract signed, then they might become very suspicious about your whole application. They might say "well, if this book is not guaranteed to happen, then there might be other things in the application that are presented in a misleading way."
If you already have a signed contract, then I think it's ok to have a mock cover, or you can use the logo of the publisher together with 2 or 3 example covers from other books published by the same publisher in the same book series.
Another important thing is whether you have good graphic design skills or not. A poorly-designed cover might show you in a bad light. If you still want to go with the idea of creating a cover, then you should make it clear that the cover is a mock cover. You could include a message clearly saying "mock cover" or something similar. In any case, you have to be upfront and honest about the actual status of your book so that it doesn't mislead anyone.
Personally, I think it would be better if, instead of a cover, you use 2 or 3 representative images of your research in order to give the reviewers an idea of what the book would look like and what its main theme is.
Edit: as pointed out by @JanusBahsJacquet in the comments section, having a signed contract does not guarantee in any way that the book will actually be published. Nevertheless, a signed contract is still interpreted by reviewers as a positive sign, because generally speaking, most signed contracts end up as published books.
Honestly, if I received a manuscript with a fake cover on it, I would think it was a bit goofy. It would not make me angry or decide to reject the work out of hand. But it likely would not really affect my opinion on the broader work.
Having a formal cover page is a good thing. I would expect that. But a stylized cover would be a bit odd.
Now, of course if you are proposing a monograph in something like children's literature, this advice may not hold. But generally, just a simple cover page will suffice.
Ceteris paribus, I like pretty things more than plain things
Personally, I see no problem with having a draft book cover including full visualisation --- it gives a draft impression of what the book might look like when it is finished. I would also find it reasonable for a draft book to include a draft edition notice page containing whatever relevant publication information is already known, plus placeholders for the rest. Just as you might reasonably have a draft of a book with a "working title", similarly you may have a draft of a book with a "working visualisation" and a "working edition notice". Both of these things contribute to making the book look "real" while it is still in draft form.
Now an important part: if you are going to use a draft visualisation, you should generally ensure that you are using visuals that you have permission to use under relevant copyright/IP law, and you should include a copyright statement to this effect in an appropriate place in your draft. If you are not publishing your draft (i.e., you are just circulating it internally for review) then you could probably get away with using a draft visualisation without permission, but you should still make clear the status of the relevant copyright/IP in an appropriate place in your draft. (And obviously, if you want to go ahead with using that visualisation when you publish then you will need to get permission to use it.)
If you end up with a professional publisher, they will of course use their own house templates for the cover pages, cover art, the edition notice page, copyright notices, and other relevant information pages. Nevertheless, having a draft placeholder for these during the writing and review stage can assist readers to see what the book might look like when it is finished. While others might disagree, my personal view is that I would prefer to see a draft that includes these elements, since it will tend to be prettier and seem more complete than a "plain" draft.
Let’s say it takes you 2 hours to mock up a nice looking cover. You could have used those 2 hours instead to actually work on the content for your book. What does it say about you that you chose to spend them doing a cover for a book that hasn’t yet been written, instead of actually writing something?
To me, if I were interviewing you I would see this as a signal that you are a person who cares more about appearances than about substance, and who wants to get credit for things before doing them; the kind of person who, say, starts a PhD in 2023 and immediately adds the line “PhD Harvard, 2028 (expected)” on their CV, or fills their publication list with vaporware “in preparation” papers, many of which will never get written. Nope. Do the work first, then claim the credit for it. You won’t get any points from me for fake book covers — even if they are only presented as part of a proposal. On the contrary, I might well interpret it as a red (or at least yellow) flag.