There's always SOMETHING you can do... pushups, crunches, dips, planks, 8-count bodybuilders, pull-ups. Atrophy kicks in after 3 days, but this can be avoided the first week, especially with smart choices at the messhall. Old guys like me dont have the metabolism that you "young guys" have.
As far as the drive out, kettlebell, perfect push up and running shoes will probably work.