Tail configuration and power system have little to do with the CG requirement.

If you have an adequate tail surface area... the proper CG will be within the normal 25% to 35% MAC range.
If the tailplanes are small and/or close to the main wing... you might end up needing to go with the flying wing range of 10% to 20% MAC.

Airfoil and incidences have more effect on CG range than the tailplane shape/style.
The engine placement will only change the thrust lne requirements. (and where the other stuff goes to get the correct CG....)

Speaking of inverted v tail and push engines has anybody seen any information on the unmanned recon plane the government has been using? Seems like that plane would make an excellent scale model.

Mitch

An inverted vee-tail ala Predator looks neat, but has two liabilities.. it needs a landing gear to keep the tips off the ground.
It limits the alpha available for takeoff and landing.
I've seen a "scale" model of the Predator, where the builder did it "properly".. tail going up ala Bonanza.
The other solution is to place the vee at the end of a couple of booms back from the wing, with the vee above the wing and out of harms way..
Check this page:
http://www.angelfire.com/indie/aeros...PhotoPlane.htm
I fly this one a lot.

.
There was a missing "a" in the Earthlink URL..
It's been fixed.
Thanks for the heads-up.
Paul

With a pusher, you may or may not have the fuel tank located behind the CG. If the tank is behind the CG, the model should be balanced with a full tank, rather than the empty tank measurement taken for a conventional model.

As other posts have said, CG position is the same wherever the engine is.
A downward vee tail does improve stability and control especially at low speeds/high angles of attack.
One way to get around the need for a long UC is to make it a tail-dragger and put skids/whells on the end of the fins. Example, the "Lazair" ultra-light. Other advantages of a pusher set-up are ; drag is lower, so speed is higher, (no slipstream along fuselage and over wing roots, tail surfaces etc ) and no yaw effects during take-off, so no side thrust on engine necessary.
This lack of prop-induced turbulence over fuselage and wing roots, tail etc is one reason why duct-fans and jets are "quick". The down-side is that lack of slip stream over tail surfaces reduces control effectiveness at low speeds, so larger areas, or movements, are required.