Can't help with suggestions I'm afraid, but I totally agree with you on the J Retro! Lots of incredible sounds available, but just too difficult to find mid-gig or mid-rehearsal...
I await the proper answers with some anticipation, as this is an option that I may well be exploring myself. I like the sound I can get from my Behringer BDI21, but I don't like the way it sucks the mids out. Is there a simple pedal that gives a mid-boost?
I really like the 3-band EQ on the EBMM Sterling that I recently traded - very musical and simple. But it wasn't attached to a J bass!