I really wouldn't use your trailer limits influence your decision to a buy a tractor personally. I have the smallest m series kubota for all the same tasks you mention. I cannot imagine doing it with a smaller machine. Get the largest you can afford. I was originally thinking the largest L series but the 50 HP tractor really saves a lot of time. I'm am constantly surprised by how much i can lift without straining it. Which is especially handy when dealing with trees. If you have a large enough lift capacity you can mechanize your firewood movement so you dont have to do constantly make piles and then load trucks by hand. Put it on a pallet and never touch it by hand again. Would you really need the main large tractor to leave your main farm that often?
I really would like a L4600/4701. Have looked into them but they are too heavy for my trailer. I really like the mx series and this would probably make the most sense, but then I would be revamping everything I have. Would then need larger trailer, which costs more, and would tow harder. My 1992 3500 dump would struggle I think with that much weight (tow fully loaded trailer with 3 face cord in truck as well), and then my 1500 pick up wouldnt be able to tow anything, so would have to upgrade that, more money.
I do move equipment off the farm alot. All the wood plots are other peoples property that have recently been timbered, and usually I am working 2 or more at once just to lock them in due to everybody seems to timber their property in the same year.
Also with the bushhogging part, I would be hauling a lot of extra weight just for an extra foot of cut width, would cost more money in towing.
But you are very right about not letting the trailer limiting me. I dont want another heavier trailer, but have thought about it many times. Thanks.