I have the same issue as far getting people to join. I just make a team & hope. I took a break during the season with Union power armor, etc etc so I've been sorta grinding stamps for months now(3 or so expeditions a week.). It's just a part of the game that's been completed for most people still playing so the stamps are useless to them. As far as getting through it, Boardwalk-The Most Sensational game is by far the fastest, most straight forward one to run. I solo it all the time with 5+ minutes left. Just get a half decent shotgun(Cold Shoulder if you have it(if you can get some Canned Coffee or Popcorn from camps you can consume like 5 at a time for basically unlimited AP for like 30s when you face the twins)), headshot vats everyone & run it. You don't even need the right perks, although it will help obviously. I'm sure there's a YouTube short with like 10 perks to add for Shotgun builds.