Question for surfers comrades

Ok I went to CA to try my hand at surfing. Had a blast but tuckered out too early trying to keep my position in the waves. I live in CO, so there is no reasonable opportunity to keep my "sport-specific" training up to par.

I can’t think of any kb drills that would remotely emulate paddling out in the waves. What makes things harder is, while wearing a thick wetsuit, you feel like your shoulders are wrapped in rubber bands.

Being from CO, this isn’t really a high priority, but I figured that if anyone knew of any kind of drills, KB or otherwise, that I could do a few weeks before hand to get my shoulders up to speed for all of the paddling I’d greatly appreciate the advice since I plan on going regularly but infrequently.

Let me say here that I am already in quite good condition, working on the fifth rung of my ETK ladders and snatching 24kg for 180 reps in 10 min. I will tell you that the SN and C+P do not carry over to paddling in any meaningful way.

Thanks!
MM