Jake wrote:
This may be a bit time consuming but if you have access to a laser
printer (or photocopier, maybe in a copy shop) rather than inkjet
which will fade in sunlight, you could try printing or copying your
field labels onto sheets of appropriately sized laser labels. These
aren't waterproof but could be stuck on whatever and then covered with
clear waterproof tape - you should be able to get a 5cm wide by 30+m
long roll for ?5-6. I've used this method to put small "signs" on the
outside of buildings and they've lasted for a couple of years so far.

Can you get "clear waterproof tape" that doesn't dry up and fall off when in
the sun, though? Scotch tape is waterproof and clear-ish, but IME it won't
stick in a permanent fashion to a lot of surfaces, and stickier tape will
just dry up and fall off after a week or two in the sunlight.