Awesome that you got out on the water,
'wanted to head out on the water over here on Muscamoot bay or
an inland lake to shake the rig down for the season, but with the promise of
storms ( that never came ), I did not want to deal with an abrupt / semi-panic
wrap up while out figuring out everything I forgot from last season.
For your Reg #'s, make up a stencil and just "Sharpie" it on
( really inexpensive / easy to touch up ~ every few months / but the Sharpie ink tends to get all over the place )
or get something like the Inflatable Boat Lettering/Numbering Stencil Kit West offers
( which has the reputation of needing to be redone every 6 months )
iBoats has the kit from SeaSense
Seasense Boat Registration Set 50091190
that I suppose if it is possible to glue the plate to your boat would be acceptable
to all of the authorities
& then there is boatnumberplate.com
which according to their warranty is at least a 10 year solution
I attached my reg tag with white quick cure 3m 5200 while the boat was inflated (needs a day+ to cure).
( I suppose you could try the same with the Reg numbers, but there was waaay to much potential
for me to make a gooey mess )
Even though 5200 is supposed be for permanent application eventually it is gonna peel away from the vinyl,
but not likely before my Reg Tag expires ( every 3 years )
( use of some 2-part vinyl glue would like result in something very permanently attached )