Assuming that there's more than one of us who's looking at a summer of both fitness and riding...
The Summer 2005 issue of Exercise and Health magazine is full of equipment-less workouts that'll be perfect for motorcycle trips:
pp 24-27: Hard Core! Killer Drills for Abs and Obliques (no equipment needed)
pp 28-30: Back It Up: A Pain-Proofing Plan (no equipment needed, and most look like they'd feel goooood after a day on the bike)
pp 36-38: "No Weights Needed" total body workout (no equipment needed)
pp 52-59: No Sweat! 3 Fast and East Workouts (1 workout uses a resistance band, the other 2 use no equipment)
p 62: Easy/Hard Abs Workout (no equipment needed)
pp 78-80: Side Effects: How to Lose Your Love Handles (no equipment needed)
pp 88-90: Get Flexed stretching/flexibility (no equipment needed)
I'd be hard-pressed to find a more complete no-equipment-needed motorcycle-trip-friendly set of workouts than what's in this issue. Though I think I'm going to photocopy the pages to bring along with me...it seems like each workout page has an ad for sexual enhancement pills on the reverse side. Eek.