Resistance bands are what you need to pack.
When I'm in India I'm using rice bags.
-bench press at the end of a single bed (double if you're big).
-Pushups for chest
-lighter rice bags for doing 'dumbell flies' on the ground
-Centred Pushups for triceps.
-Light rice bags for biceps.
-Carry heavy items on your forearms and squat up and down.
-You can also do this and then do walking lunges.
-If travelling with a small child, you can use them as weights too (seriously, they love it)
-Pull ups are great if you can find the right stuff.
-High intensity sprinting will also have some muscle gain effect if you don't sprint that often
-If you know how to safely lift things, then doing that repetitively is also very good
I've tried all of the above, and they do work quite nicely (some balance issues involved with the larger rice bags, but it works).
Give it a go