There isn't much of anything left to remove from the airframe.

If this is an electric or small glow powered plane (slow flying ), fit the pieces and use ONE DROP of thin CA to glue each joint. The joint is not as strong, however, the covering will provide some additional strength.

Minimize any epoxy used.

Use a light weight film covering - do not use paint if at all possible. If you have to use paint, remember, clear is the lightest of paints (dope ) and colors add weight rapidly. Check the weight per sq ft/yd between different colors on the coverings - there is a weight difference between colors also.

Do not add weight to balance the plane, shift the battery (or use a larger battery), and receiver, or use a larger/heavier motor. You want any added weight to be "working" weight, not dead weight.

When you build light, you often times can not build as strong. You will not be able to do hard/rough landings and your violent manuvers will have to be minimized/eliminated.

MOST people, when building light, use contest grade balsa (4 - 6 lb balsa ), thinner thicknesses and a light weight covering. Unfortunately, the majority of kits have balsa in the 8 - 10 lb range and the parts are typically thicker than you would want to keep everything light. Scratch builders keep EVERYTHING at the minimum weight/thickness needed to do the job.

I do a fair amount of sctatch building and frequently make "balsa plywood" for pieces that do not require the strength (or weight ) of light ply (fuselage formers in back of the trailing edge of the wing ). I also do things like using balsa for spars instead of basswood or spruce, HOWEVER, I do reenforce them with carbon fiber to maintain strength. Other things I do is to increase the spacing between ribs slightly to eliminate a rib or two and I look for areas that I can use lighter/thinner materials with minimal sacrificing of strength (1/32" sheeting instead of 1/16" sheeting, 3/16" square balsa instead of 1/4" square balsa, 1/16" thick wing ribs instead of 3/32" or 1/8" thick ribs ). You get the general idea. Each item by itself doesn't account for much weight, but together, they can (and usually do ) add up to some significant weight savings.

If you want to invest the time (and money ), you can frequently scratch build an identical kit plane and the scratch built will be several ounces lighter than the kit plane.