Re: Make your bass sound like a rhythm guitar and bass at the same time
So then you'll lose the bass guitar in order to have twin harmonized solos and rhythm guitar, but no bass.
Give your bass player a doubleneck guitar/bass and have him switch.
Or get a harmonizer so the rhythm guitarist can do rhythm, the bassist can do bass, and you can play your harmonized solo without any loss.
It's actually a lot easier to get by without the rhythm guitar in a live setting than on a recording, as the sound pressure level is more than enough to compensate.