Rick, if you'll be using it for serious flying and not just test gliding to find out how the trim works I'd suggest some 1/8 sheet for the wings so it'll withstand throwing it hard and the inevitable "tough love landings"   You could even install a peg about half way between the nose and leading edge and extend the fuselage stick about an inch behind the stab and glue a wrap of medium sandpaper on it.  Then two or three #64 bands looped together to form a long bungee would send it aloft with fine style.

Harryangus, the elevator trim in the case of sailplanes is our throttle.  As such it is a primary flight control.  On the old movable style levers I used to extend the elevator trim button by drilling and threading in a 1 inch long 2-56 screw so I could find it easily.   An airline pilot with previous jet fighter experience that used to be in our club used his elevator trim frequently to trim for different power levels and for landing approches during flights with all his power models.  In full size airplanes the elevator trim is also a very frequently used control.  Almost to the point of being as important as the joystick or wheel.  A lot of us modellers see it as a one shot correction for new models and use all manner of tricks to try to avoid using it.  But it isn't any sort of admission of inadequecy to use it a number of times in a flight.  To me it speaks of a pilot that knows more than many that he's willing to set the trim for such things as landing and takeoff and again for the "sporty" part of a flight.