I feel that there are two ways to go about it:
a) Get a real toneFULL guitar and amp that does not need to be loud to cut thru OR
b) Tell the whole band specially the drummer to back down on the volume to let you cut thru
Option b) is easier than option a).
Since I used to play guitar and NOW am learning to play drums, I learnt that the drummer sets the overall volume of the band. And if you cannot cut thru, then your drummer has poor skills in dynamics and overall musicianship.
Can't agree with FM55 enough. When folks say "your band is only as good as your drummer", the reference wasn't only in time keeping skills, but also with volume management.
A heavy handed drummer in a small area is frustrating to the listeners and players. The rest of the band's response to this (if inexperienced) is to turn things up louder.
A good group listens carefully. So discourse among bandmembers about volume and eq in the mix is very important. You'll notice with more accomplished groups is that they actually "back down" when it's a soloists turn. Listen to any Allman Brothers live recording. The rhythm section is as smooth and bubbly as a jacuzzi, slightly softening to "lift" the soloist, and responds to certain licks.
But when they hit the peak or climax of the solo, it's still controlled. There's a ceiling to the volume.
Talk to your band. Talk to the soundmen. Lift those mids as well, eq things during soundcheck.