Wow, this topic has gotten some traction )
This is what I've found:
A) The Oceanis and Hurricane lines are all 200+ prims and require you to wear them, for reasons stated above.
B) I decided to use my banline HUD (https://marketplace.secondlife.com/p/Explorers-HUD-Essential-for-all-Vehicles-Explorers-and-Landlords/1269113 HIGHLY recommended. I use if for riding my motorcycle. The HUD shows where the rezzable water is among other things, so if the boat does break apart (ie, you stood up), you can motor to the rezzable spot and do a quick repair.
C) Motor Loon has created a new sailboat called the Oceanic, which is under the prim limit, it's mostly phantom, however at sea you can stand up, walk around, anchor and go ashore for a short time. You can get a fully functioning demo at the Tradewinds Yacht Club on Dex (143,64,25). It appears to be a VERY popular boat, I see them coming by my house almost constantly the past few day, it has a Main, Jib and a Spinny. He makes excellent motorcycles, and this first entry into sailboats appears to be a winner.
D) No one stands up in a moving vehicle, not even me. My contention was that if I'm at sea, with my GF, and choose to anchor and go below, I should be able to. Guess that's not in the cards.
If I can throw a recommendation in while I have your attention, I picked up a nice little speeder to get around on the water to check out some areas and I have to recommend it. It is the "Wave Cruiser 3" (https://marketplace.secondlife.com/p/Wave-Cruiser-3-Classic-Beige/3263671 This is a fantastic little speedboat under 32 prims, and it flies. I used it to shoot over to the Tradewinds from my dock, jump out, read the description of the Oceanic, jump back in and zip home. For only $55 Lindens, it is sooo worth it.
Thanks for everyone's input, and for those highly knowledgeable people who spelled out the specifics for me. I've been here about 6 years, and I've never stopped learning.