I have 2 guitar tracks that I am routing to a stereo buss. Within each guitar track I inserted a send. I pan each guitars send to the opposite side and set the send to the same buss as the original routed tracks.
 
I dropped the sends volumes to around -5 db less than the original tracks. Seem to give me a fuller meatier guitar sound, but still maintains a good stereo image. Probably not an issue right? I mean whatever sounds good?

You may run into problems when the song is listened to in mono, whether summed to mono or only one channel (such as people sharing earbuds or in most shops).

You might run into phasing issues.
What i've found that helps is to send to a bus (panned hard left & right) track, and set a really fast (slapback) delay with low feedback on 100% wet.  Just enough that you hear the guitar again slightly after the original track. It might give you a meatier sound without any phasing risks.  Or simply another fun way to build on your guitars...
 
But yes, whatever sounds good works.