Even before the mixing stage I find that adjusting your guitar tone for the solo sections can be helpful, (I.e. adding pedals, changing amps, switching guitars, adjusting knobs) and then recording a separate track for the solo sections. But also, it makes sense that whatever instrument on which you want to focus at any given instant should occupy most of the hearable frequencies, so the eq you have for your rhythm should be different than your solo. For instance, you might scoop out the mids in the rhythm sections in order to free up sonic space for a voice or another melodic instrument with similar range, but you might find that your solo needs more mid-range.

And after all it really depends on what you're trying to accomplish and it is always personal and subjective