When I went to winterize my 02 GT325, I couldn't find a potable water tank drain either. In the end, I ran the water pump into the kitchen sink until no more water came out. I used an air compressor attcahed to the city water inlet and blew through all the faucet lines and the toilet line until no more water came out.
I drained the water heater by removing the anode rod. Then I went to the dump station and emptied both the holding tanks. I just put the pink stuff in the p-traps, on the assumption all the supply lines were empty of water.
I think the coastal plain is probably free of frost by now. Although they had snow in Bellingham yesterday, the temp was about 37F.
I've been sidelined by a lumbar disk problem that needed surgery, so our season will start later than anticipated this year. A month of physiotherapy starts next week. Hope to be out by the first wek of June, or maybe a week earlier.
BTW, there's a NW Region Meet & Greet of iRV2 website members in Anacortes, May 12 - 15. Would you be interested? We'll be going in as day visitors, since we live about 4 miles from the campground where it's being held. Check "irv2.com/forums" to find details.
Frank and Eileen
No longer RVers or FR owners