Go search for conversions of Sig's 1/5th scale J3 Cub, with the regular wingspan, as opposed to the clipwing. At 84.5" span, it's 'real' 1/6th as opposed to the ready made world's IMAA legal 80" and a little bit, but close enough. I electrocuted a Sig 1/5th some years back, but if I rattled off the battery size and motor configuration, you'd think you were reading a history book
High wingers are a royal PITA to set up for battery swaps. Mine had a two piece wing and scale access door in the fuselage, so I sat my battery on the cockpit floor, hard up against the back of the firewall and re-charged it in place. Like I said, it's a while back, when batteries didn't have a rep for blowing up if they got upset over charging.
In your place, I'd be looking real hard at A123 packs, maybe 5 or even 6 cells, so I could install the battery, a safety device to unhook it from the ESC and charging point access.
Hope that helps