BillH:

There is a certain small effect of having prop tips close to the fuselage sides, but so long as the tips are just close it's not to worry about.

All else being the same, the twin with closer spaced engines is easier to fly with an engine out.

Tanks? Header tanks are not really a solution, You see the header tank and the remote main, the carb still has to pull the fuel from the main tank to the header tank. The engine sees the total length of fuel draw, not just from the header.

Muffler pressure is not a solution - if one engine quits the pressure from the other blows through the tank and vents through the exhaust of the dead engine, and you then have two dead.

The Cline system works fine for a single main tank, the header tanks are not needed.

My favorite way is using pumped engines, or a Perry mump on each engine. Works fine. And still doesn't need the weight of the header tanks.

Your three piece wing should be fine, it's the way I would go.

And there's no reason not to make the plane a taildragger, but I don't think the nose gear brackets etc. would really interfere using a small format camera.

Engines. The TT46 engines should have enough power, but you're going to be adding some structural weight also, you might think about the Magnum 52 engines for that little extra.

Bill.