I'm writing a paper as a Ph.D. student, and I'm starting to feel a little bit unsure about the general approach and results. My supervisor isn't a great help here, and I thought to maybe send a preprint to a couple of authors with more expertise than me, whom I cited a lot, and ask their opinion and if they would find it of interest.
Is this appropriate? I wonder if it would look like I ask them to work as my reviewer or supervisor for free, or I would even look like one of these crazy persons sending researchers their huge manuscripts with fringe theories. On the other hand, I would get feedback during peer review anyway, so I'm further unsure about it.