Hey J&L !
I like your game and like how its growing and becoming bigger and bigger.
So my suggestion / idea is really simple : stockpiles of logs.
I don't know if any one suggested it already but it would be great as logs takes a lot of space if you have tons of that. I'm very familiar with game called : Wurm Unlimited (telling name of game not like advertise it but like an example).
There was same problem at starting of game that players didn't have a lot of space , so dev's bring in stockpiles of logs.
Please find attached pic how it looks like (sorry for quality of image not best one).
Probably community will share my felling's about it as well.