Decals will hold up just fine if they're applied correctly on an absolutely clean surface.
Check out
www.aerographics.com. They're nice folks, specialize in airplane graphics and decals and can give you all the advice you need to do a good job. Lucky for me, they're local... right here in little 'ol Loveland, Colorado!
If you're up for the extra work, they can also do stencils for painting. That's what I'm doing for my Midget Mustang, but I can confirm that it's substantially more work!
Best regards,
Rod Woodard
Loveland, Colorado (KFNL)