Clothing- Wetsuit alternative?

I never wear gloves so can't comment on what works there but adding wetsuit socks inside your hike boots should keep your feet nice and toasty. Just make sure your boots have enough room for the extra layer, if you cut your circulation to your feet off then your feet will freeze no matter how many layers you have on them.
I have a similar question - What clothing would be the equivalent of a wetsuit? ie what layers would provide the same or similar warmth?
I wear a set of 3/4 hikers (magic marine until they were stolen over 4th July) with a zhik thin neoprene top for most days in winter. Water is 55-60 deg F. Air is 40-70 deg F.

As air gets colder and wind gets higher I add spray top & a hoody fleece.

I wear boots and different combos of gloves depending on conditions
Ya Glen, I thought you looked pretty funny out at the lake in just you swim trunks. j/k

Last we sailed was early November with temps in the 70 degree area and water temps near just as warm.

Swim trunk are a good idea if you only go sailing on warm days (here in Austin, Tx).

And now, you've said you put your laser away for the Texas winter.

No worries, I'll be reminding you of the Easter regatta at the lake!

Keep in mind that wet suits come in many different flavors as well... there are separate top halves, overalls (Farmer John/Jane) etc and several different thicknesses available if that works better for you (I've never worn anything but swim shorts and a t shirt on a boat - but I'm a diver too).
RE: Water temps - I sail lakes, It took me a while to find a website providing water temps on a daily basis, but the one I found is good and covers the whole U.S. so far, even the most obscure lakes I've searched for has been supported.

Unfortunately I don't have a link for coastal waters...