I used tuff coat on my tin project. It works just like painting any other bare metal- scuff, etch primer, then paint away. it's pricey compared to traditional paint but the finish adds a lot of value and utility to what would otherwise look like a homemade boat.
i used lines that were already present on my boat- the benches and the little stubby deck that comes on the front of lowe jon boats. i got those level (with the boat on the trailer) and then worked off of those lines as my data. i figure lowe had a pretty good idea of what their status would be...
probably will be fine in the short term but if you want this to be trouble free, i HIGHLY recommend tinned wire. bare copper wire will corrode too quickly when left to the elements.
i used a piece of 1" conduit cut at 45 degrees. thinner wall cuts easier but will also deform easier under pressure as you turn it. you just press it in, turn it over a couple of times by hand like a drill bit, then pull it out and take the foam out of the cavity in the center. perfect diameter...