Basiclly, what I built is a bunker right behind Old Longfellows house. It required me to use some of my caps to buy a shipment of concrete and one of steel. Scrapping a lot of trees on the island provided me with more wood than I could possibly need. At least for now. I also built a small shack for NPC's if I get the urge to expand the settlement a bit. Most important is some reliable source for food and water. I could build a water purification system but that would probably leave my base vulnerable for attacks. I hope my current build does not attract the wrong kind of attention.
This is my bed room. Cozy as ever! Yes, I have one or two mods that affects settlements and provides much more options than vanilla Fallout does.
And this is the living room I guess. I just needed some display area for various stuff I pick up. Like Vim and Nuka Cola. And the magazines. Feeling satisfied with the base for now I decided that instead of advancing the main quest I should do some exploring of the island instead. I had my sights set on the northern parts since they are within comfortable reach from where I am. And it seemed like there was going to be good weather to boot!