Farmbuyer just a crude drawing but I'd cut the floor between formers 1 & 2 and split it length wise use a Dubro nylon pinned hinge a standard control arm like what you would use on an aileron and a couple of bellcranks. You'll have to make up something to hold the bellcranks to the insides of the fuse and your own connecting rods/push rods to operate.I'd stay far enough away from the formers so that I could lay in some 3/8 or 1/2 inch triangle fore and aft of the opening and maybe a small piece of flat stock or allow the tri-angle to over lap the opening by say 1/4 inch so the doors have something to close against. I'd use a standard servo depending on the weight your putting on the doors. what do you plan on using for a radio. You'll also have to make something to hold the servo. this is interesting let me think on this a bit and see if I can maybe draw something up for you.

egor