I use an amp sim called Vandal on these, which led me into a couple directions.
First, after noodling with bad metal licks courtesy of a much improved overdrive tone, I was able to settle into a good tone that really helped my guitar solos.
Second, Vandal includes bass amp options that led me to trying to replicate a late 90's Primus like tone using my fretless P-Bass played with some aggressive slap style ala Claypool.
I give you 2 selections:
Stank - Upbeat and definitely intended to hit the Primus style. I'm no Ler LaLonde on the guitar, but I was trying to be a bit off center with the licks.
Diversionary Tactic - Much slower tempo with some cool L/R bounce in the guitar tracks. Also, even though it's still a bit sloppy at points, I feel this has the best guitar solo I've ever pulled off.