RE: Hold cowl from inside?
Ditto on the wood cowl ring-on a round cowl its easy-for 1/4 scale use a 1/4" ply ring, with attachment holes drilled at appropriate locations. I usually add an extra layer of fiber glass to inside so ring can be glued in and also glassed. I.D. of ply ring can be shaped to get around any obstacles. Socket head screws make it much easier to attach and remove cowling.