Yep- got the G being the V of either C chord, as well as the ii (half diminished, no?) /V7/ i progression. I just thought that it's funny how the G7 "works"- sounds fine to the ear, even though it would be a G-7 if the progression were strictly diatonic.
How did you work around not thinking modally at this G7 chord? Just sticking to the G, B natural, D, and F?
One way around it is (got this from a Joe Pass book and the local keyboard guru who only seems to think in chords) With dominant chords you can alter the 5th and the 9th. If you think about it this covers all the notes except the raised 7th over that G7. 1 b9 9 +9 3 4 b5 5 +5 6 b7.
There is so much you can do. the first tensions I was taught were using chord tones from a Db7, or a flat 5 substitution.
If you want to think in terms of modes, G Phrygian Major, Super Locrian and Half Whole diminished are common.
If you've got G B D and F down it may be best for Roy to cover the next logical step. (You might add the b9 to the mix for starters, Ab)