I did a short Amtrak trip last fall during the pandemic. Train to Seattle. Ferry to Bremerton. 1st night at Illahee state park (almost in Bremerton and nice biker campsite). Second night in Manchester State Park (town of Manchester a couple miles away and good restaurants). Then to Tacoma through Gig Harbor and across the Tacoma Narrows bridge to catch the train home.
Illahee State Park might be a better choice for your first night than Manchester since you may want to minimize your miles on the first day after getting off the train.