We were in Skagway in late May. We did not see any large parking areas near the ferry terminal to leave an RV and TV. I'd contact the ferry ticketing office to see what they have to say about both locales.
BTW...we've been to Valdez, Seward, Homer, Denali NP, and of course Anchorage. Our workamp commitment prevented us from going on to Fairbanks when at Denali. We hope to make a run to Fairbanks for 5 days with a side trip to the Arctic Circle. Also need to get back to either Homer or Valdez to go halibut fishing. The 3 days we had available to fishing in Homer, our charter canceled due to very high seas.