Since I seem to gather that you do a lot of gigging in different styles, I would go for a second bass if you can afford it and have the space. After all, the number of lefty electric bassists and upright/double bassists is slowly increasing, now that we are no longer seen as spawn of the devil or sumfink... It's a matter of ordering a bass and waiting, as opposed to walking into a shop and grabbing one, but at least you're usually no longer met with a scornful laugh and a head-shake.
You may well be able to sell on your spare bass - if one day either becomes surplus to requirements - to a younger musician. Or even to me, if I ever manage to move into a bigger flat!