heres my experience with them... (plz dont killme people!!)
When I was a lot younger, and my family went to the beach, I would always catch these guys (its waaay to easy, walk around the shoreline, if your heel sinks, dig under it, never fails (can get snails and clams sometimes too)). Id keep em in 5 gal buckets over the 5-6 days id bee there and change the water and sand every couple of days or so. Never had any deaths, and thats 5-6 days of 0 filtration, etc... tho it was seawater...
IMO they are very hardy. And now that I know abit more about what they need, they shoud be easy to keep if u have enough sand for them to bury in, and decent flow. Probably adding phyto/zooplankton to your water should keep em happy...
Not 100% sure about all this, but still, hope it helps!