I just figured a nifty trick to build my cottage with tons of logs/boards/slender trunks/whatever. First, you choose a spot, to be your settlement. Next to some river or shore. You start the cottage, that gives you an icon in the map. Now, this trick assumes you're making your cottage very close to the tile center (mine is 8x8 exactly in the middle of the tile, which is 50x50 squares) This is the spot where you normally appear when you zoom-in with enter.
You get a raft or punt, with a paddle, and go around the shores chopping trees and pushing them into your raft. Try not to chop trees that are too far away, like 2 or 3 squares away tops, so you can drag them quick, then move on. Repeat until you have all the trunks you want, including slender ones, specially for floor/ceilings. Now, get into your raft, move into the water, zoom out and go back to your settlement.
Now, here's the thing: you can zoom in/out on top of your raft and it will stay with you, with all the stuff on top. So, on the overland map, you move into the settlement, which will zoom you in automatically, except closer to the edge. This is the part where you normally would start moving your crap, but instead, hit enter to zoom out with your raft, and then zoom back in. This time, you'll spawn in the center of the map tile, where your cottage is, with all the stuff on top.
This is of course only useful if you're building in the center. If you build close to the water, just move your raft normally, park it on the shore and move your stuff.