You liked that "toes" bit didja?

There was an F3d model a few years back that used closely spaced tandem wheels in a belly fairing. The design was actually published in RCM. It was the world champ that year.

Unfortunetley I believe that Q500 and maybe Q40 have landing gear rules that specify non tandem wheels and spacing that precludes "cheating" like that.

What can you do within these rules? Probably not much other than preventing gaps that turbulate the air. The conventional gear places the wheel close to the final vertical part of the aluminium gear. This will create a small gap that will generate some turbulence in the grand scheme of things. All I can suggest is keep the wheel VERY close to this last little vertical bit and file that part so it's flat on the wheel side and airfoil shaped on the inner face with a countersunk bolt for the stub axle. Arrange some setup that then allows the axle to be firm but keeps the wheel within a paper thickness of the vertical part and has a blank outer axle cover. For the rest of the gear just file and polish it to a nice airfoil. Lots of work so don't land hard on it.....

You also need a minimum cross section. If it allows in the rules make the fuselage a bit pod bellied so the landing legs are shorter. And use the minimum sized wheels they allow and make them out of aluminium with a small O ring tire...... Starting to sound like Formula 1 isn't it?

I don't know how much of this you can get away with as I understand that the rules are tightening up to make the racing less gimmicky and more sport minded. But all in all the little things help. Using internal surface actuator linkages for example.