Understood. Then you don't have the right mics to do the job, I'd say. The Lavs will only get you so far. That's why Shures are still a standard everywhere on stage for vocalists, for example. I shoot acoustic guitars and mandolin a lot, (I have played both for years) and you need something other than lavs for those. Routinely I record professionals who bring $1000+ mics to record vocals and acoustic instruments. It's just a totally different game than when you use an amplified instrument. My personal mic for my mandolin is a $350 Sennheiser evolution (which was the mic used by our recording engineer when I recorded a CD in 2006). It has to be close mic'ed to get a decent sound. By that, I mean inches from the sound hole. The lavs range is too limited for this work, IMHO.
I have found that unless you are getting paid big bucks, at which point you should simply hire a sound pro and get them to mic and run the levels correctly, that the board mix, while tuned for the hall and the audience, will get you much closer to an accurate portrait of the sound than what you are talking about doing, in most club situations. It's not that you can't make this work, but I think it will be substandard to your ear. I do all EQ after the fact with the board feed, as do the sound guys that I hire on occasion. I blend my camera mics with it to achieve presence. Sometimes the board sound is not correct, but usually it is. I recently had problems with the addition of an accordian to the stage, which was mic'ed too far back to be any good.
You can hear examples of my work at markpearsonmusic.com as all the videos there were recorded by me, with a sound engineer present. Here's one I recently rolled out.
https://vimeo.com/44265835
Controlled studio like setting in a big hall. We used neumann's for guitars and shure's for the vocals. Also on vimeo my channel has a long list of lower budget live recorded acoustic music, some of which are recordings of some of the top mandolin and guitar players from Brazil.
https://vimeo.com/41474125
Believe me, they understood recording their instruments. The live work for them was done with board feeds, and EQ'd after the fact. It's all about budget. If you have it, then I'd hire a pro, if not, then like me, you go with the best you can get, which is usually a board feed.
Al