Another beaten to death Solar question. Please help!!

Agree with the above. Around 250 watts is a good place start and will keep your ~160 AH battery bank charged daily on good summer days. That size will also service a twin 6v GC2 battery bank when you upgrade those grp24s

Start with 250 watts and good 20 amp controller (like morningstar sunsaver) and you can add a little more solar in the future if you need to.

I have 265 Watt solar with a morningstar prostar 15amp controller and the 265 watts will come close to maxing it out if the bank is low