I could actually try using the 7.4v Thunder Powers. I happen to have them lying around without much use since all my electrics use 3 cells these days.

From feedback I collected, the adjustable Fromeco regulators have heat sinks and dissipate heat quite well. I can save weight and a regulator by sticking a 4.8v for ignition. DA says you will get a spark all the way down to 4.3v.

I just saw a guy at my field today flying a 87" Extra he build from some kit. His plane was well over 19lbs. and the DA 50 had no problem tossing it around, doing all kinds of 3D stuff and pulling up out of hover.