-the solenoid is commonly relocated to the engine compartment - water and weather failure is more likely than failure due to elevated temperatures in the engine bay
-HD connectors are commonly used to isolate the winch when not expected to be used - this will ensure not drain from a leaking solenoid, but would be inconvenient if you had to pop the hood to connect while mired in the mud etc.
I built my own bumper and mounted it beside the winch itself covered from rain and snow, but close enough to use the existing wiring on it. I'm wired direct to the battery, but test it occasionally for amperage draw.
'00 XJ Sport, White - almost done for now...
'11 Town and Country - people mover :-(
'88 XJ Up Country, '01 XJ Sport, '08 KK Limited, '98 XJ Parts Donor, '07 XK Limited (the Stall-ander)