ppkk, Unless you plan to enter the model in a contest where appearance will earn you points...reinforce the center section!

Remove the monokote back far enough to expose about 1/4" of bare wood outside the tape you choose. Mask off farther out where you don't want the epoxy to run. Bottom and top tape get done in one process, but it takes two steps...Do the bottom strip first, wrap up & over an inch or two LE and TEdge, cutting a bit to surround the mounting tab at LE and forget for now about the wing mount bolt holes at TE. (They can be cleaned out after)

30 minute epoxy allows plenty of time to do this job.

About epoxy: I have done a some research and found in general, manufacturer's claim that epoxy is not to be thinned! However, I have been thinning it for years with dope thinner, and have had no problems. Go figure!

Batch amount: One time, I estimated how much epoxy it will take to do the entire job then mixed the whole batch at once. The result was shortened cure time! Seems as if the curing process got accelerated when a large amount got mixed at once.

Many use Finishing Resin, which is thinner than epoxy and the end result looks really good too. Search and find out more about it.

You can paint the completed center section and not bother with monokote. If you cant match the red...paint it black, or another color to match other trim for example. The properly joined wing halves are more important than the final overall appearance IMHO.