i suffered the same thing--L4-L5--following a season of mountain bike racing [i'm a life-long roadies, and do mtb about every fifth year] where i had NOT done sufficient core strenghtening the winter before. i tried all sorts of crap, and always got back too soon, and would relapse. epidurals never worked for me. what ultimately did was chiropractic treatment, yoga, and more and continual core work. it took me two years, wherein i went absolutely CRAZY without serious and regular cycling workouts and competition. it has been five years since my back issues, and i'm much better. i LISTEN to my back--it gives clues and wonderful feedback--and we are very happy. i've had three major crashes [MANY broken ribs, three clavicles and a scapula, two concussions and a collapsed lung--seems like a lot when you drill it out like this] since then, and my back has never given me grief. i'm entering my "off-season" -- cyclocross, and a long winter of outdoor gravel riding and weights downstairs to get ready for next year's racing. i'm 57 [according to usacycling], a category 1 racer, and i LOVE this stuff.
best of luck to you, dan. GIVE YOUR BACK THE ACTIVE REST IT NEEDS. but do NOT just sit around; STAY ACTIVE. DO YOGA. STRETCH. RIDE YOUR BIKES, and don't resign yourself to recumbents. treat yourself properly, and you'll be fine.
i hope!
--kim