Hi Little Beck,
Sunscreen and latex seals,...its a great question, and one that the dry suit industry has not really addressed.
DEET mixed into sunscreen. (insect repellent) is really tough on the latex so avoid this mix if possible.
Ideally you want to avoid oil based products when wearing latex seals. After using any sunscreen, rinsing your seals in fresh water after each use will help.
I’m not sure if there’s any oil free suncreen on the market thats waterproof.
Have you had your suit in the water yet? How’s it working for you?