I never boost behind solos, and never turn on a pedal just for that reason either.
I either enjoy the space, or I re-write the bass part to make the arrangement work better for when the mix sounds "thin".
I do a variety of things but aim to build the bass part as the guitar solo is building. Assuming 4/4 time - roots on 2 beats in the bar, then rising to all 4 beats to add some momentum, then maybe some octaves linking the root and octave with the kick and snare, and then make the part a walking line to get up the neck a bit
The order of all that depends on the song and the solo - it could all the other way round if that suits better.
But no amount of pedals can fix an arrangement that needs improving.