The cable wiring you have is right and should work fine without any audio disadvantages.
However, if all you can get is a mono board feed and you have a 2ch recorder, you might record a mono board in one channel and throw up a single mic for the other channel. That way you can just copy the board onto both channels in post if you want, or it also gives you the option of mixing in some of your ambient mic with the board and then copying both the resulting "matrix" to both channels. It will still be mono of course, but you can use the mic to round out what could be a pretty dry board mix.