On my CJ, I put the solenoid box under the hood (REP8000). Been that way about 20 years now, no problems (and I do use it).
No reason not to as long as all the cables are of sufficient size....the wires aren't any longer overall...just the box is in a different place other than directly on the winch.
Only thing I can think of is not to put it where it will get too hot -- i.e. mine is on the "cool" side of the engine bay (straight six, pax side, not the driver side where the exhaust mani is) and is where it can get some air flow (not boxed in by other stuff).