Between what you can carry and what you can put in a cart without overloading it, you might be able to create a 'portable' main base. You could also do it with a longship but for a karve would need multiple trips or... well there's a way to get a cart aboard perhaps even broken down into crates and barrels - still rather iffy. Raft.. lots of trips .. would build bridges as far out into the water as possible at each end and keep the raft trips as short as possible, loading/offloading from/to chests on the ends of the bridges (ok piers lol).

The big issue to me would be the chance of getting hit with a raid at poorly defended waystations and outposts (which you'll probably want a lot of). Not going to get into it because it may be spoilerish but there is a way to build minimal 'outpost lite' min-bases that are not subject to raids (other than the one that comes after you wherever). If you want to go that route check the wiki on Raids and Events, triggers, and think about minimum requirements and build orders. Quite possibly paranoid overkill but then again, permadeath..

With no portals you're going to need lots of roads and ports. I'd suggest using an adhoc approach and being far more concerned with function and time required rather than appearance or convention.

You can build 'swim' ports rather easily - just a pier (dead end bridge to nowhere) jutting out in the water with a workbench and some chests. Use the 26d roof to make like a bumper that you can stand on for cargo transfer. When parking your boat, move it out almost as far as you can swim and make sure the boarding ladder faces the shore. For added safety, make a raft and leave it halfway between. If mobs go after something it'll be the raft, better to lose it that the ship. The raft also serves as a 'regain stam' place.

For roads, I only use the hoe and traditional roadbuilding techniques in areas that are suited for it - basically fairly clear relatively flat areas that won't take forever to terraform into a road. For the rest, I've found it faster to build wooden cartways; anchor to ground, tree, post, or raised earth as necessary. its just 2 - 2x2 flooring pieces side by side for cart hauling. Use the 26d roof pieces to change elevation. I prefer to alternate sloped and flat sections and not to chain more than four or five in a row so you can run with cart up them without running out of stamina.

For ravines and the like just go full bridge across that part. In areas that brush up against or go through black forest or swamp, I'd elevate the roadway using raised earth sections as supports - keep the whole roadway up around 10 meters or so.. If you want you can pass through swamp like that using the Forever trees when available and make it a covered bridge/fighting platform as well as a road.

If you don't care about looks and don't try to make everything 'perfect' you can pretty much build that type of cartway using the rocks and wood you get from clearing the way.

Yeah long winded as usual, hope it helps! Good luck Rogue!