Yea, you need to do some talking out of game, and/or realize the GM doesn't like casters, and make something else... Other alternatives include buying a portable hole and a necklace of adaptation at high enough levels. Then go there to sleep. Presto, no interruptions. It also works great for sleeping while the party is traveling.
Other interesting ideas along that line:
"The wizard does not have to slumber for every minute of the time, but she must refrain from movement, combat, spellcasting, skill use, conversation, or any other fairly demanding physical or mental task during the rest period."
So, as long as you don't DO anything even if you are woken up, then you've gotten the appropriate rest. Since you weren't gonna do anything anyway, why bother to get up? Unless the enemy gets past the meat shields, just set up a place to sleep with full cover from ranged weapons (get a special mobile/collapsable tower shield type setup). Then you're fine just laying there and watching combat.
Edit: Addition...
You can also maintain a mostly casterish aspect while going the arcane trickster route. Of course, I've never attempted that without starting as a rogue, it's always harder to shoot for a PrC after the character's been started up.