Keep in mind that working on a boat this size is vastly different and much easier then your keel boat. For one thing, all the parts can be brought home to a garage, shed or even just covered with a tarp outside. If you are not too proud you could even use a thin tarp or an old used sail to make a knock off for the simple triangular form the lateen rig uses. I think I have even seen used sails on craigslist for about $100 and used complete boats from around $500 on up.
The Sunfish would be a nearly ideal boat to just 'knock around in the local lake' on. When the wind dies you just raise the dagger board and use it as a paddle to get back. The hull is a little heavy for single handed car topping IMHO but the rest of the rigging would be easy to bring and take home each time, if the hull were locked on a rack or somewhere near the lake.
There were tons of these boats made and many knock off brands came out that use very similar hull design and rigging, so used equipment should be easy to find.
I wasn't trying to scare you off by mentioning that older hulls can and usually do take on some water; I was just being honest. The same is probably true of a similar boat that is popular in the mid-West, the Butterfly, which you might also consider. Butterfly Sailboat and Butterfly Sailing News, Information, Events, Results, Parts and Accessories, Used Butterfly listings
It's rigged more like a Laser which you also might like.
I have access to a bunch of Sunfish about an hours drive from home and really enjoy the times I find myself sailing on one when I'm not on my Tartan 27'. One of my best sails last summer was on a Sunfish with a friend in winds gusting near 20 knots. We got that sucker planing on a broad reach and were flying - and hiking out and getting wet. I don't know how fast we went but it sure felt like way more then the 6 knots our T 27' can do on a similar course.
Fun boats but wet.