From a pure sound control standpoint having everyone go direct (no stage amps) and getting the drummer an electronic kit so everything goes through monitors & PA is the best solution. There is nothing loud on stage (like trying to cover an acoustic drum kit) but your monitors & PA need to be good enough/powerful enough to deliver the bass, drums (especially the kick), etc. with enough punch that you don't sound like karaoke tracks. Which also means getting the guitar player to give up his 100 watt tube combo that he HAS to run 'dimed out' to get his sound.
It's much easier to just work as a group (gee what a novelty!) to control stage volume. All direct is great for a sound guy, but honestly you'll find a shortage of musicians willing to compromise their gear and play direct. Musicians spend a pile o money finding "their" sound, which is fine if they take the time to learn to play as a BAND instead of a bunch of bedroom w@nkers showing off. If you can blend the band without the need for anything but vocal PA...stepping up to full pa is not a chore at all because everyone is already aware of their levels and how to fit into the mix.
Playing as a group....another lost art form. :scowl: