The big claim to fame for those Selig airfoils is that they handle higher wing loadings with some tolerance. But they don't make high wing loading models fly any slower.

The big thing for the A-10 is the seemingly slow lower range flying speed and tight maneuvers. For that you want some camber and a lighter sort of model weight. If you are after that appearance in the air you'll want to aim at a flying weight of more like the 7 to 8lb range instead of 8 to 9 lbs.

It might be worth looking at some model airfoils with higher camber as well. Something like the Selig 4233 is a thicker airfoil for more stiffness and strength combined with good low speed characteristics and a fairly high maximum lift coefficient. Another good airfoil that worked well for me on an old school electric glider back when these things were all fairly heavy was the Eppler 201. It slows down nicely yet still allows for some scoot all while carrying a higher than optimum wing loading. "Higher" in this case being higher by glider standards. Not by big scale model standards. There is no free lunch to THAT one.

Given that the props set up as pushers would be eating the "dirty" air off the nacelles I'd suggest twin tractor props sitting just in front of the "air inlets" of the nacelles. And as much as possible make the nacelles flow through style tubes with the motor mount on fairly thin supporting "wings". The props in this case will still see some dirty air off the wings and forward fuselage but it'll affect them far less than trying to eat the turbulence off the nacelles directly in front of the props. The payback for this selection should be more pull from the same amps of power or same engine power. And if running engines and not electric it means more effective cooling for the engines.

All in all an ambitious and interesting plan. I wish you luck with it.