Not owning a dob, I can't help with the spring question. I often drape a tarp over my set-up scope at night, If I take a break from viewing just to keep the dew off it. But I wouldn't just drape the tarp over it & leave it out for day's on end. I'd rather see my OTA inside under cover! My EQ mount is a permanent fixture, so I built a sheet metal cover with wheels on it for it. I guess you could do something similar with yours? leave the dob mount out under a tarp or something & just bring the OTA in?
But a dob base being made of wood, you may have a problem with moisture/warpage etc in this weather. So probably not a good idea..