I would use something like:
Thanks for staying overnight last night, or simply Thanks for staying last night
Thanks for yours overnight is not an expression we'd use at all, in any situation.
Here's a definition for "overnight"...
o·ver·night
adj.
1. Lasting for, extending over, or remaining during a night: an overnight trip; an overnight guest.
2. For use over a single night or for a short journey: overnight supplies.
3. Mailed for guaranteed delivery on the next day: an overnight package.
4. Happening as if in a single night; sudden: an overnight success.
adv.
1. During or for the length of the night: Let the meat marinate overnight.
2. In or as if in the course of one night; suddenly: became a sensation overnight.
n.
An overnight stay or trip.
intr.v., -night·ed, -night·ing, -nights. (o'vər-nit')
To spend the night: overnighting at a country inn.
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The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2000 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.