Can you straddle the speed bumps over one side? I've got a few of those square ones near me, the type that if you took them centrally your sump would get a little bit close. I always move left and let the offside go over them, while the nearside stays on the road.
Maybe something like the VWR springs would do the trick. They don't drop as much as H&R/Eibach. And I would recommend doing the shocks too. Again, VWR sound good, and cheaper than Bilstein. I've done a couple of years (maybe 15k) on H&Rs and original shocks. All was well for a while, but the shocks really do get tired, quite quickly, once you're running them at reduced travel.
New coilies are waiting to go on some day soon though. More fun with speedbumps!