Well, I see this a couple of ways.
You could get another bass that you downtune, and throw lower gauge strings on it (BEAD sorta thing).
You could get higher tension strings so that they're not as floppy when you downtune.
You could get a hipshot extender (
http://hipshotproducts.com/cart.php?...t_detail&p=260) for easy downtuning.
And I'm sure there are other options. That's just what came to. I think for me, if I'm playing downtuned about as much as standard tuning, then I would rig up another bass.