Van Tail Lights

Personal experience says that once they start leaking you'll never succeed in sealing them :-((
Two options;- 1. Drill a hole as you suggest. Cheapest way out but depending on how much water they take in the contacts will eventually rust and then not work. 2. Replace lights with proper sealed units like those made for boat trailers, or, if the lights are old, simply replacing with new units with good seals may do the trick.

Gday Matt,I changed all the lights on our van to led, they are sealed and you never have to worry about globes failing or shaking loose,also much more intensity.A bit dearer but well worth it in the long run,rear lights can be bought as a single unit,blink/tail/stop or separately.they wire up to your existing cables good luck,Keith C

Half your rotten luck Mate!
Wouldn't mind wet tail lights down here in SA.
Mal.