Pushup variations - clap, triceps, elevated, weighted
pullups
dips
one-legged squats (killer!)
abs -crunches, raises, v-ups whatever
that would make a pretty challenging full body workout..
or if you want some conditioning/gpp work, maybe a circuit of
skipping
burpees
sprints
that should be enough if you did those a few times a week to make sure when you get back you wouldn't have lost much strength.
If there is a park nearby you can find some sturdy iron to do your pullups/dips/hanging raises!