Hi Jim, I use the same method as you with spray finishes - both urethane and lacquer. I keep a small jar with a screw lid nearby half filled with celulose thinners (similar to your mineral spirits) and once I have finished spraying anything I take off the nozzle and leave it sitting in the jar till the next time I need to spray anything. I just remove the nozzle and dry it with a paper towel and fit it onto the can. So far I haven't had a clogged nozzle. Just my method.
Keith.