I have an old Mac Venture 25.
It's a fun lake boat
and I use it for sailing with friends and dropping an anchor
for lunch at sandbars and swimming around the lake in the summer.
As with all trailer
boats, it's squirrely and unbalanced because I've got a 500 pound hunk of steel
for a keel
- so "built for sailing" is a very...arguable... term.
I've never been on a trailer
sailor with a drop down keel
that wasn't a compromise firmly on the side of "trailer" rather than "sailor", but they are wonderful for what they are designed for. So I'm not sure you'll find what you're looking for. I think the Venture is a great example fo the breed - far better than the 26 MacGregor that's even less of a sailor and more of a motor
sailor than anything else.
And, yes, my boat has two through hulls - one for the bilge
and scuppers out the back, and one for the sink - both above the waterline (I think - memory is fuzzy on the galley
Good luck and I hope somebody chimes in with another option for you.