Textbook advice for hiking footwear seems to be: wear cushioned socks!!! And make sure your boots fit!!!
For me, it seems that wearing a cushioned sock ensures that a boot simply will not fit comfortably. Ever. But many arguments I hear in favor of wearing thicker socks suggest they make the boot fit better, so now I am wondering how important sock weight really is, provided the boots fit in the first place.
I have wide feet but they're "shapely" rather than boxy. So my foot is wide where the toes start, but it tapers significantly towards the heel. I also have a high instep and arch. I'm not convinced that my foot is particularly high volume, I think it just has funny proportions. Usually when I find a boot that is not crushing my instep or forefoot, the rest of the boot feels very sloppy and too loose. Heel slippage is consistently a problem. I've tried various tying techniques to no avail.
When I throw cushioned socks into the mix, say smartwool midweight hikers, it seems to exacerbate these problems even more. Thicker socks don't seem to solve the heel slippage problem at all, and while they make the overall fit more snug and a bit less sloppy side to side, very often they make a potentially comfy forefoot or instep area painfully, unworkably tight. I currently wear thicker socks with boots that are the least painful I've found, but I can't say the fit is "good".
SO. Searching for new boots, I found a pair of keens (Wander WP model) that seem to fit very well, with thin wool running socks (smartwool phd ultralights, to be exact). Unfortunately they fit so well in combination, that's the ONLY sock weight that I'm ever going to be able to get into these boots comfortably. But there is extraordinarily little heel slippage, the instep is reassuringly snug without being tight, there's no side to side slop, yet my forefoot/toes are free and easy. Note I did try the boots on at the end of the day, when my feet are at their worst. They might be a bit more swollen in the heat, but I can't really simulate that.
Preferred hikes are in the baby Alps, but these are all well traveled and maintained trails with stable surfaces, albeit rocky in places. The most challenging aspects are they can be steep, and one can be walking with significant cant/camber for long stretches, which I have found very difficult in lighter weight shoes as they just don't offer enough support on these tilted surfaces. Otherwise, loose stone, rain, mud, cowpies and occasional snow are the worst of it.
So the question is: what pitfalls could I face out on the trail if my boots actually fit, with the tradeoff that I am limited to only wearing non-cushioned, relatively thin socks?