Interesting reading through all this. I play solo all the time but I run full mixes including drums, bass guitar, digital guitar and live keyboard at times. When I play a keyboard solo, I bring in a guitar auto strum, and when the keys solo is over, I mute the auto strum and carry on with the digital guitar.
I always had trouble performing and trying to mix my own sound. I have spent hours at home adjusting levels on the PA that I use live. But sounds always change according to the environment. So, I mostly adjust the bass guitar using a fader mapped to the bass output. I do get into trouble when the crowd noise gets a bit loud and I have bother hearing my PA volume. I have used floor monitors in the past, but I have been experimenting at home with IEMs for the last few weeks, so that I can get used to the latest and greatest setup in the universe due to arrive at my house very soon.
Last October, I ordered a 3DME In-Ear Monitor setup. I’ve just had word that the company has stock, and mine should arrive in the next week or two. These things are special in that each ear piece has a built in microphone and these allow the user to dial in any amount of crowd/ambient/room noise they need. This will allow me to lower my PA output and boost the in ear volume to a level that suits me. I will also be able to adjust the bass guitar volume if it seems too loud. The unit takes a feed from a mixer output without volume control. There is an app (of course!) that allows the user to adjust the various levels including stereo etc, and also has a limiter to help prevent you going deaf. Some folk apparently remove one IEM so that they can hear the room. This is not a good idea because if it is done too often, the listening ear can get damaged by trying to compensate. This damage can be permanent I believe.
I sold my floor monitors and used the money to pay towards the system. It is costly at $NZ1,600, but if you read up a few user reviews around the net, they all say that the money is well spent and that they wish that they had done it sooner. One fella mentioned that if he wants to hear what the drummer is saying, he just looks at him and picks up every word clearly through the IEM mics. Https://www.sensaphonics.com