Simplest way?
Connect your winch to the Cranker
That way the Aux is only going to see about 1/3rd of the load if you even need it.
An SBI12 Redarc will do to parallel the batteries
Some of the other VSR's are rated at 140 to 150 amps
The heavy duty SBI12 from Redarc is rated at 200 amps as are a few others but they are quite expensive