On mine you can remove the telltale and stick a flushing adaptor in the threaded hole, but I don't bother (partly as I don't have the adaptor and when I enquired it was F expensive but mainly because I can't be bothered). The aux that arrives in the next few days has a similar arrangement, a bung on the bottom of the engine which you can screw a hose adaptor in to flush it without the engine running.
When it was in the water all the time it rarely went more than 2/3 days without being used so I figured there was no real danger of salt crystallising out, but now I take it out during the winter, I flush it each time then leave it trimmed right in to drain out so it doesn't get frosted. Time will tell if I am doing the right thing or not but it seemed to be sensible to me