Cindy brings up a good point...if her volleys are weak, then you will suffer as a mixed team, *especially* at open and higher levels.
I'm in the camp of 'go on out and give it a shot even if you're going to get your arse kicked'. So, if she is up for it, I would say go for it, but be very realistic with her and tell her what to expect.
And then forget the groundstrokes, and work on volleys. Fast, hard volleys. At her face. At her body. Work on positioning and communication. Make sure she can serve where you want her to in order to set you up at the net.
Oh, and did I mention serve to her a bunch, too?
You guys may not be ready for the big time yet, but if she keeps working and getting better, and gains experience, it sounds like you may have a mixed partner for a good, long time! Good luck, and keep us updated!