Thanks for the picture Steve. That's just what I needed to see. If you have a picture of the support to the roof for the standoff, that would be fantastic.
As for the roller, it is also being considered. We don't have many of them down here either. I used to haul the anchor over the stainless trim on the side and top of the gunnel. Worked fine. I just thought the davit might be nice to have. Roller might be more suited to my boat. Are they available commercially or do you build them yourself?
I don't have a pic for the support but a lot of the one's i've seen are either just a rod that holds the davit out in the hauling position or a 2 piece hinge type that folds up and out of the way when not needed.
I would think it would be easy to make up a nice simple roller , maybe just a short piece of pipe with a lobster block hanging off of it, hey how about putting a rod holder near the hauler so the short davit could plug into it for anchor duty and when not needed pull it out and use the rod holder for a rod or gaff.
Check out Cape Fisherman's Supply they sell a lot of small boat longline gear and i'd bet they have some slick gunnel rollers for sale.
I built this simple hauler for my bowpicker and used a piece of angle for a davit, it bolted on with a couple of bolts to the hauler mount so when i didn't need it it was quick to take off and stow.