This should really go without saying, given that it's called the Nexus 7, but we'll go ahead and say it anyway. Yes, you can unlock the Nexus 7 bootloader, then have your way with it however you deem fit.
Unlocking the Nexus 7 is the same as any other Nexus device. You'll need to put it into USB debugging mode, have the Android SDK installed on your computer, and then use the fastboot oem unlock command. (Relocking is just as easy, too.)
So, no worries on that front.