What type of sail plan & rig is best for solo sailing?
Thanks for your responses.
Opinions vary on this one, partly due to sailing style/preferences, ability/experience, and sailing grounds.
In the size range you are looking at, there really is no need to split the rig with two masts, as on a ketch or yawl. I might even go so far as to say you probably don't need to split the headsail plan either (as on a cutter), at least for 90% of the sailing you'll do.
But many bluewater sailors prefer the cutter or double-headsail rig, which allows a combination of a smaller headsail and staysail to be used. A lot of coastal sailors prefer a fractional sloop, with a smaller headsail and more drive in the proportionally larger mainsail.
For shorthanded sailing, I like a sailplan that makes it relatively easy to "switch gears". On a typical modern, fractional rig, the first downshift usually amounts to flattening the sails (snugging outhaul, backstay, etc). On less "tweekable" arrangements, reefing the main or downsizing the headsail is often the first step. This is obviously more labor intensive, so a solo sailor might want to consider a more tunable/tweekable rig that can get you up to the 20 knot range without need for sail changes or reefing.
Then again, this approach might just amount to postponing the inevitable.
A double headsail or cutter rig with a 3-reef main, properly rigged for single-handing, might be the ultimate solution for the widest range of wind conditions.