The swamp is an easy place to build a base that can not be attacked/destroyed in my opinion, the keyword is "treehouse".

The larger trees cannot destroyed, they are high enough that blobs cant jump up, and its easy to find clusters where you can build in between.
Just build some ladders around a tree until you are about 3 to 4 walls high and place floors with a few angle´d girders to support areas further away of the trees, that way the only things that could be attacked are the ladders.

It is also possible to build a fireplace up there if you have iron for stonecutter already, a stone slab close to a tree with enough support from the tree.
The only thing you have to carefull of are ruins, they can spawn a wraith in the night and those jolly things would just fly up to the base to haunt you :D so build as far away of those as you can or you can also build inside them to block the spawn.

I build a treehouse close to a bonemass spawn and a second swampbase in an old stonetower right next to a plainregion with a yagluth spawn, both work just fine.