The vent hose, except in extreme overfill and heeling conditions shouldn't get that much challenge from gases. The real challenge comes from fluid (especially urine in saltwater -- when followed by the other stuff we load in marine toilets).

I think you should be fine just replacing the hose with a quality sanitation hose which is "black" -- you don't want to encourage growth from sunlight in the hoses.

Is the line really coming up into the stanchion base and then being vented-out? Have you had any issues with the sealing of the penetration in the stanchion base area?