I don't know Brit...maybe try it for a week and see how it goes. I think the IL's sounds like a better option than the hotel though...only because the hotel may be difficult with your D.
Can you extend the deadline for where you are now at all? Maybe even by a week? This would at least decrease the time you'd need to rely on your W's place.
Part of me thinks why not give it a try and see how it goes at your W's...what do you have to lose? Literally, weigh out what you may lose by doing so against the benefits.
At least you know your D would be comfortable there and if you (just you) had to go stay elsewhere for a night or two you still could.
Sorry you find yourself in this situation and sorry I'm not much help! J~
M 35 H 29 M 4 yrs T 9 yrs D 3 S born 10/19/07 Bomb 09/10/07 Separated next day OW - broke up and H moved out 09/07/08 Status - still figuring this out