Personally I see no reason to fit dual batteries for a winch - simply install the largest capacity battery you can, or, if physical space is the challenge, fit two smaller, identical batteries and parallel them - you can run a dual battery system with no isolator - the purpose of the isolator is to allow electrical load to be powered from the secondary battery whilst the engine is off and the primary battery is isolated so that it will retain enough charge to start the engine - when the engine is running the isolator parallels the batteries so that the alternator charges them both - you're not going to be running the winch when the engine off so if there will be no "off engine loads" there is no need for isolation.
Throwing a 12v stove into the mix takes us back to loads that are going to be run whilst the engine is off, which takes us back to dual batteries and an isolator (or dc~dc charger), and in this case since you will want the batteries paralleled whilst winching, the isolator would be preferable - take a look at the current draw of your winch, divide that by two (identical batteries should share the load evenly), and that will give you the current the isolator will be required to handle.
As mentioned before, it is not a good idea to parallel batteries that are not identical - ideally, for best results you want the same chemistry, same capacity, same voltage and the same age - anything else reduces the longevity of both batteries - and if you're planning on extended/extensive winching, consider an alternator upgrade.
Non identical batteries will result in uneven sharing of the load, one battery being depleted before the other with consequential deep (or over) discharge of the smaller battery and subsequent premature failure - how long this takes to happen will depend on how deeply the batteries are discharged.
