Well you're getting increased heat on that side and if the brakes are checking out then its got to be the hub bearing/s. modern bearings are pretty bomb proof and don't generally have catastrophic failures. You've checked for play and not found any, have you checked for rumble when turning the raised wheel, it should be silent from the bearing. compare sound and feel with the other side and there might be a subtle difference in feel and or noise. Next time you go out feel the inboard side of the hub, caution here as it can get very hot with a problem, holding the axel at the back of the hub will often allow you to feel a roughness when rotating the wheel even if you can't hear it. My experience of bearings starting to fail are just as you have described and even a phisical examination might not show anything to the human eye buy it certainly doesn't mean its not reached the end of its life!
For years if I replaced a bearing in a wheel I would always do the other side at the same time but latterly I've reached the conclusion that I'm wasting my time and money and if all checks out with a rudimentary inspection and there are no other issues I leave it as is!

Hope that helps you clarify your problem a little better but all I'd add is that if you can't find a obvious problem then it's the bearing!