Add a shoe-box to Your luggage and put a TRX in it, maybe a jump-rope too
-> http://www.fitnessanywhere.com/
The YMCA might be a little more flexible with out-of-town member visits,
and they are all over the place, but quality of facilities can vary
significantly. Outside of that, the best You can do is try to find a gym
that allows one month memberships.