The doors on the TF Spit is pretty much left to the modeller to design and build. I started out planning on making them out of some 1/8" basswood sanded to match the contour of the wing which would be attached with a bracket and screws on the struts that screwed into blind nuts on the doors. My first attempt turned out too fragile, and one of the doors split. I also purchased some of Dave Platts videos, on one of which he describes the method of making a fiberglass sheet on the surface of the wing, then use the fiberglass sheet to make a door that matches the wing perfectly. Of course, I got this video after I had cut the wing skin away from the area of the wheel wells. I ended up tack glueing some sheet balsa to cover the wells, and made the fiberglass doors on top of it. This gave a door that was close to the shape of the wing.
Mounting the doors was a bit of a puzzle to me. I knew that I did not want screw head on the exterior of the doors. I decided to combine my original basswood doors mounted with blind nuts and the fiberglass covers. I drilled countersunk holes in the basswood for the blind nuts so when the blind nuts were installed, they would be flush, or just lower than the surface of the wood that I would glue the fiberglass on. As a result, the blind nuts actually stick out on the inner door by about 1/32". This may be what you are seeing as a spacer. As for the brackets themselves, they were a challange to get right to give the proper spacing and alignment. Each bracket is made of several pieces. There is a brass tube that is a press fit over the strut. To this is attaced two pieces of brass that make up the actual bracket. This whole assembly is JB welded into a single bracket. It took time to bend and shape the pieces to allow a flush fit, but when complete, no additional spacers were needed. My doors don't fit inside the wheel well, but sit in a 1/32" wide and 1/64" deep groove that runs around the wheel well. The final fit is pretty close, with just a slight pull up on one edge. Another thing I did was to drill holes through the basswood parts of the door, turning it into swiss cheese. I then skinned the inside of the doors with thin mylar. I also had to cut a slot in the wood to allow for the back of the axle to travel as the strut compresses.

Scott