I wouldn't shoot a wedding, as a primary, with just those two lenses, personally. I have worked a wedding as a 2nd shooter with just a 50mm prime before, but for the main shots (especially ceremony) you want something that will allow you get get a close view without being close and in the way yourself, i.e. a 70-200 2.8. Renting the 24-70 2.8 is a good move. A back-up camera so you won't miss shots while swapping lenses would also be a good decision, with the added bonus that you have something to work with in case your main camera goes down. Losing all those memories because of a camera failure... would be bad. As far as NEEDING a full frame camera to do "serious work", I'd have to argue slightly. I know a few VERY SUCCESSFUL wedding photogs that work with DX only, but I'd say... at least... a D7100 or similar. Something with a more pro setup on the controls and a bit better low-light performance. Full frame would be NICE, but not necessarily a NEED. GLASS is the more important need.
Make sure you've got some sort of diffuser or softbox for that SB-700! Sounds like you've used it before, though, so perhaps you already knew that.
BIG challenge with the equipment you've got, but... Good luck! (and sorry for the rambling approach)
Oh, and welcome to the forums.