At least think about the possibility that the following may be true:
Your greatest problem is your embarrassment about being associated with work that is nontrivial and somewhat interesting, but not very ambitious.
I can't speak for other academics, but this ailment afflicts many (most?) mathematicians. Rota famously quipped that the worth of a mathematician is taken by evaluating their worst paper and dividing by their total number of papers. So it would be best if you wrote one paper (or one paper which anyone ever saw) which, say, resolves singularities in characteristic zero, or proves the independence of Cantor's continuum hypothesis, or....
Look, you worked for 10-15 hours alongside of other people and you proved something. Rationally speaking, what is the argument against writing it down, trying to get it published, and including your name on it? I don't see it, really. Isn't it more professional to record what you spent time working on? It would be different if you wanted to push the matter further, but it sounds like you don't.
Well, thanks for listening. Let me now directly address your questions.
1) Is there any polite way to opt to keep my name off of it?
I think that if you just said, "Sorry folks, I just don't really feel comfortable having my name on the paper" that would be the end of that and no one would view you as being impolite. It does have the possibility of inspiring others to do the same, and at the end maybe the thing doesn't get formally written up, but that's still not really impolite unless there is some author who really wants and needs it to get written up, which doesn't sound like it's the case. Nevertheless one can ask whether it is really ethical not to take credit for your own work.
2) If this thing does see the light of day, would it be acceptable to omit it from my CV, or list it in some different section?
It depends what happens to it. If it doesn't get published, then certainly it should go in a different section of your CV, and if you don't want to include unpublished papers on your CV then that's your right. If it gets published, then in my opinion you are ethically obligated to include it on your CV.
How are these sorts of papers viewed by hiring committees? (My impression is that they are not uncommon these days.)
That's a great question (the best question, I think). This kind of paper is increasingly common, and hiring committees have the task of what to make of it. I want to say though that certainly they do not in themselves make a negative impression. The problem is if too many of your papers are so-multiauthored (or multiauthored with the same senior people well known for their expertise in the area) that it just isn't clear that your name needed to be on them. But that problem is fundamentally a problem with your other publication record.
It sounds like you are afraid that in publishing such a paper and putting it on your CV you are advertising it as being as good as any of your other papers and asking for "full credit" for it. But you are doing no such thing. In fact it is the hirer's job to decide how much credit to give you for all of your papers. If you do not take steps to signal the importance of the paper and your contribution to it, I think most people will see it for exactly what it is: something nontrivial but nonmajor that was done relatively quickly at a conference. What's wrong with that? Nothing.
The last thing I will say is that having a few of these papers could help you more than the stereotypical mathematician is willing to admit. Contrary to what we get told in grad school, when you apply for a job, although (perhaps) some people are evaluating your research with an eye towards its total mathematical contribution and likely future promise, (certainly) other people are counting your beans. Having enough beans is not a sufficient condition to get hired (or tenured or promoted or...) at a strong institution, but it is probably necessary. Every once in a while someone who seems really good doesn't get tenure at a good place (I have in mind a relatively recent instance of this at a top ten math department). What was the problem? In each case I have seen, their number of beans was on the lighter side. Make sure you have enough beans, and don't be embarrassed about it.
