RE: large DF Bombers
Welcome back!
The advances in electric power have been incredible over the last decade. If I were a manufacturer of glow engines, I'd be very concerned about long term prospects for the glow engine market. With the improvement in electric power and the availability of the small gasoline engines, more and more modelers are giving up glow engines.
How about a B58 Hustler? That's something you don't see everyday. That big delta wing, with pylon mounted engines, would make a natural for electric flight. Wouldn't need to use ducted fans, motors with props in the front of the pylons would be less expensive and perform better. A nice feature of pylon mounted engines is the ease in which you can exchange powerplants. You could start with props to work out any problems with the airframe, then exchange them in pairs for ducted fans.
Good luck!
DT56