Since I became and ARF man, my thumb has gone through allot of rules ( ha). One is to keep the plane and toss the hardware. I know they mean well but it is not worth it. Number one on the list is the fuel tank.

I'm a ARF and OPP man myself (Other Peoples Planes)
Personal preference and experence usually determines wether or not you use the provided "stuff".
Clevises, horns and pushrods are usually the first items to be replaced followed by the wheels and engine mount.
I've found most fuel tanks to be OK with the exception of the fuel line that comes with them. If I do choose to replace the tank, it's for a larger one. You can mount the radio gear any place you want and that goes for the tank as well. I'm just about done with a Global 60 Trainer. I've mounted a Canon H8 video camera in the nose ($199.00 from Fry's) Two Thunder Tiger 36 engines in the wings using Hobbico Twin Star necells, Perry pumps and a 18 oz fuel tank mounted under the center of the wing so it's inside the fuse. I'm using the inside "third " of the ailerons as flaps so there are 6 servos in the wing. Two throttle, two flaps and two for ailerons. Two more in the factory servo tray for the tail.
The point is, you can do anything you want to them.
You don't have to follow the instructions or even the rules
but of course you have to keep safety in mind.
Have fun, be creative.