With an OS 91 FS up front

I placed my reciever and battery to the rear of the compartment that is visible when the wing is removed.

I would have moved it farther back but I did not want to take the time to make a hatch. So I added 3 more ounces to the tail

I was shooting to have the CG at 6".
I am at about 5 or so now.

OS 91 FS just isn't enough power for me.

If I had it to do over again I would go with a saito 100.