I use magnets to hold my cowls. I have to be careful as I can break apart the cowl trying to pull it off the fuse.
The cowl will also avoid moving side to side. The little magnets are VERY powerful and weigh very little.
I'm using 1/4" x 1/8", one magnet in the cowl and one in the fuse on one plane and two in the cowl and two
in the fuse on the other. I have a small dowel in the front spinner ring. The cowl is not coming off during flight.
Nitro planes would work the same.
Mine came from
www.kjmagnetics.com