I sail my DS II solo, it works for me. You will want a tiller estension to allow you to sit on the windward side deck sometimes for added stability, amazing what a difference it makes! ALWAYS sail with the mainsheet i nhand, use the supplied cam-cleat to hold the tension, but always keep the mainsheet in hand to allow releasing the sheet if a gust of wind hits and allow the boat to more easily stay upright. The DS can be quite easily sailed without the jib for more more relaxing sailing (not as fast, but it works fine!) Two people can make the whole thing easier, true..... but I've found the boat pretty easy to sail alone (but then, I've been sailing my DS II for 18 years now and had a 12' Widgeon before that. I grew up sailing a 1970 CAL 21 which had a deep keel, but even that was not beyond what either my Dad or I were comfortable sailing solo.
The RHODES 18 is a nice boat too, a bit bigger but the same width as a DS II. That is a heavier boat with a much heavier centerboard (or are you looking a a keel model?) I think that I'd miss the cuddy on a Rhodes 18, that is one feature that I like on my Day sailer, Back when the R18 was first built in fiberglass they did have a little bit of a cuddy, but still not as big as on the Day Sailer. Then again, Cape Cod Shipbuilding definitely builds a good, quality boat and they are still in business and ready to supply any parts you might need. The Rhodes 18 should be able to be easily sailed solo even using both main and jib, maybe easier than the DS due to location of the jibsheet cleats being further aft and closer to the tiller. I think you may find the DS cockpit more roomy that the one on the Rhodes 18.
If you are looking for a boat like the DS, but a bit bigger, you might want to look for a RHODES 19, O'DAY built quite a few both centerboard and keel versions. They had a cast iron CB, 165# and so would be a bit more stable than hte DS, the keel version even more so, but with a 3'3" draft... not as easy to trailer. The cuddy on the Rhodes 19 is a bit bigger than the DS and on the older O'DAY ones you could almost sleep in there. The cockpit is a bit bigger (wider anyway) than the DS, and will probably be more comfortable.
The DS will be easier to trailer than either the R18 or R19, especially if you get one of the newer ones (1981 or newer) with a hinged maststep (or an older one that had the optional mast hinge added). The Rhodes 19 from O'DAY had that option as well and I think that Stuart Marine (current builder of R19 and Mariner) made it standard. The Rhodes 18 has a mast stepped through the deck as did the earlier O'DAY-built Rhodes 19s. If the R18 you are looking at does not have the hinged mast, Cape Cod Shipbuilding could sell you the parts to add one or you can get the parts from another mast builder. For trailering a hinged mast makes stepping/unstepping the mast a lot easier!
