Love
this Thermos thermal tumbler. Doesn't spill/leak so I just put it on the mattress and lean it against the wall. If it falls over, it doesn't matter. Do have to remember to open/close the lid when drinking it in this manner, but it works great and no trailer modifications necessary.
Other reasons I love it:
- disassembles for easy cleaning
- drinks like drinking out of a mug (i.e. lips on a rim rather than sucking out of a hole)
- keeps drinks hot/cold a long time
- easy to flip from open to close and back again
- smallish base so fits well in any cupholders