BillS, and others:

There are two commonly modeled twins that are really bears on a single engine; the P-38 and the B-25. Less commonly modeled, but still nasty, are the F7F Tigercat, and the Martin B-26 Marauder.

Things to avoid: Wide engine spacing, short wing span, short after fuselage, small rudders, high wing loading, and overpowering, among others.A lot of the problems can be lessened by dropping the 100% scale demand. On my "Tiggerkitty," for example, (my avatar) the engines are a lot closer than scale, and the vertical fin/rudder are almost 150% of scale. It is still controllable with a single engine at full throttle all the way down to stall speed.

Just some things to think about.

Bill.