Mike I agree and am also a user of test stands. In answer to your question the most simple is just a length of 1x6 lumber with a notched cut out in one end for the crankcase, then just bolt it to the board just like an engine mount. The Board can then be transported to the field and drywall screwed to a table or clamped.

Of course you can get as fancy as you want or spend as much as you want. I use are four old alumin Tatone mounts which just clamp the engine beams with a a large bolt. This is bolted to that 1x6 and the tank is banded to a step block behind to get differant fuel heights. I even got fancy and made an articulated lever behind that uses a simple "S" bend push rod to operate the throttle and it has a friction adjustment.

The reason I have four is I prefer to break in my multi's all at the same time all screwed to the same table so all the harmonics are the same as in the airplane.

John