Trouble is Mt Rainier is too far out of the way from MT ST Helens. You could go to Mt Rainier Cougar Rock CG but then would have to double back to get to Mt St Helens Windy Ridge or go back to I-5 to go to Johnstone Ridge Observatory. JRO there is a $15 per person charge to see the show. There are many CG in Gifford Pichor NF but some roads are not trailer friendly. I think you should choose one or the other. Mt Rainier Cougar Rock or Ohanapecosh CG is very nice both can handle large trailer or MH. Both have Dump Stations and water. Mt Rainier should be showing it beauty this week very well. However make your reservations.
