What sounds good live typically doesn't good on tape.    Best success in the past has been with two mixes -- one live, and the other a mix down to however many tape tracks you have, preferrably by an engineer in a different room but if not, headphones can work.

But it sounds like a little 8-track recording could do the trick for you. A live engineer could eyeball the levels to tape while mixing the house, and you could mix down later at your leisure. This will require a thorough sound check to achieve a decent degree of isolation, and get ya'll used to the different setup.

I agree with PJS -- hire a whole package. Trying to piece people and equipment together will be much harder, and likely more expensive anyway.