Since the Wright brothers first flew at Kitty Hawk a huge number of aircraft have been designed to meet specific requirements from passenger transport to various military applications.
Lifting body aircraft include two basic types.
One is used to slow re-entry from orbit.
Another seeks to maximize efficiencey in terms of carrying passengers and cargo for the least fuel consumption by having the cabin part of the aircraft also provide some of the lift. This was the idea behind Northrop's flying wing designs in the late 1940's. More recently Boeing is experimenting with a V-shaped body that also functions as a wing. Two or three jet engines are mounted to the wing/body in a pusher configuration. In one proposed Boeing design the aircraft might carry more than 500 passengers who would sit inside the wing.
A lifting body configuration would be a poor choice for an indoor duration rubber powered aircraft. It would be difficult to meet the minimum weight and still have minimum wing loading. The airframe would also generate excessive drag.
The laws of physics and aerodynamics dictate a tractor configuration for max duration in indoor rubber powered free flight classes, i.e. prop in front of main wing, with the stab and the rudder on a tail boom. At least 80 years of effort have gone into perfecting this basic configuration, resulting in one hour flights for F1D class airplanes.
All that being said, you can still have a lot of fun, and learn a lot, from building and flying other indoor rubber powered configurations. A classic pusher is exciting and looks very different in flight. This is where you have the prop behind the main wing and in front of the stab and the rudder. Another fun design to build and fly is a canard pusher, where there is a small wing in front of the main wing. Neither pusher design will be competitive with a tractor design, unless a sufficient bonus is awarded. Multiple prop designs are also fun, but again, they will not be competitive with a single prop tractor design.