Guys, thanks for your helpful replies.
Ed, adbass, fingers, I do use my fingers to achieve a different volume/tone/inflection when I'm in a small group/small room setting. However when I'm with a seven piece Dixie outfit on a big stage in a largish hall I have to turn round to my amp and put some extra vol on to make my solo heard. Due to limitations in our PA speakers the bass does not go through them and so everything comes from the back. I can't put too much vol on when comping or my colleagues complain, particularly the trom who stands in font of me.
So, rakiksey & Jostein congratulations on reading the exam paper correctly and answering the question. I'm playing about with an LS-2 at the moment and it seems to help, although I do detect a slight tonal change as the signal passes through it. I will get a GEB7 and try that ($140 in UK!). This will have the advantage that I will have the option of modding the EQ for the solo as well as the vol - it could for example lift it in the middle.
bolo, you seem to play with far kinder musos and audiences than I experience. Interesting, however, your point regarding leaving the first two bars out. I do that from time to time and it works! I remember playing to 3,000 Germans in their town square - Speyer, I think. We were playing 'Dans les Rue d'Antibes' by Bechet. It came to my solo, I walked right to the front of the stage - almost off the apron - waited two bars and gave it to them. They went wild; you don't forget days like that! I think the local wine helped and we had very good sound on that tour.