I think in the long run you would be better off with peel back decals (stickers) or else hand cut trim from Monokote. Not "Trim Monokote", just more regular iron-on Monokote.
Fuel proofing water slide decals takes a good coating of really fuel proof clear, and putting that on top any iron-on is questionable at best.
These planes, finished in Mono with Mono trim have lasted a long time for me.
Excpetions; the indian head, FAI, and Smilin' Jack are computer printouts with FasCal over them.