I built mine several years ago and it has a couple hundred flights by now.

I covered after it was all glued together. I made fillets between the fuse and wing and made a strip over that to seal the fuse covering and the wing covering.
Petie 2nd was covered in as close to the real plane as I could at the time. There is a real P-51D at the Waukesha, WI airport with the same paint scheme.
It is covered in Monocoat. The antenna s routed through a hole up through the fuse and routed at scale out the 'canopy' and back to the top of the tail.

It is a FUN fun fly plane, and I have won many a contest with it!!!!!!![8D]