As others have said it should be possible. I sideload Android packages to my Kindle Fire all the time since the Amazon app store lacks many of the apps I use, including all the Google apps (Gmail, G+, Maps, etc), so doing this to the N7 should be no different.
Also there are a number of ways to do it effortlessly, and I'll wrote-up a tutorial when my N7 arrives. Honestly though I'm not sure what apps I'd need to sideload though since most if not all the apps I use are already in Google Play.
Sam