I store my boat at home and tow it every weekend to club racing about 30 mins away. Not being a member of a club is a foreign concept to me.

How do you get rescue/start boats at regattas that aren't held at clubs? Do the regatta organisers also organise people to supply and man boats?

We usually leave this up to the club that is hosting the regatta, whether it be a class championships or an all-boats style regatta.