That is very encouraging to hear.
Yea, I know the reason for wanting to use a bigger prop. The plan would be, as you described, to use 3s (2x 2200 mAh in parallel) and swing a 11" or maybe 12" (I got a lot of 11x5.5 props around). But I'd much rather use a bigger 650 kv motor with a 4s and 14" prop. A bit slower prop speed and more thrust (rather than more prop speed and less trust like the 1300kv motor), it would bring more scale like qualities to the flight and slow things down a bit and give more thrust rather than top speed when you need to get out of a bad situation.
Thanks, back to the topic
I'v seen people use as big as 2200 mAh receiver batteries on big planes. But that might be overkill
I just personally don't like to hassle with 2 batteries and I try to use a big BEC for example when I use more servos. Also for FPV stuff I rather take the servo voltage and boost it to 12 V rather than use a separate battery (or separate BEC) for the FPV gear. But I haven't really build anything this big so different kind of forces might be in play.