I need to come up with red or orange waterproof tags to mark my muskrat sets for a muni job I recently acquired. Needs to effectively say "City authorized trap, do not remove or tamper". It also needs to attach to the top of 3/8" fiberglass rod because that is what I use to stake and/or mark my sets.

Assuming this is a common requirement for muni jobs. What are you using to mark your traps?

My traps are tagged with standard copper tags with required information. You could get copper tags made with your message. This would give it a long lasting, professional look.

If you wanted something handwritten and don’t care much about appearance, you could cut tags out of laundry detergent jugs. Wash it and wipe it clean, and then you can write your message with a permanent marker. This is how I tag my recreational crab and turtle traps.

I use this a lot. You could probably get some outdoors stickers made quick on vista print or someone similar.
The flags took a while but it was heavy COVID time.

How about lawn signs? They're pretty cheap and can be made to look very professional.

Blank calf ear tag, and proper marker are weatherproof, and fairly professional looking