It is more than doable. It isn't actually that difficult of a game to begin with. There are a few things that are made easier or quicker by having more people.

For example you don't need to plan your home portal before leaving if someone else is still waiting at home. They can just link a portal for you from their end whenever you're ready to come back.

Another benefit that you will miss from playing coop is that you can move as many boats full of cargo as you have players. Solo players need to do more metal runs because of this, even though they don't need as much metal as a group would. Alternatively having multiple players fill up a single boat will obviously make for quicker runs too.

I would also argue that combat is a bit tougher in solo. Even though enemies increase their health and damage in the presence of more players, having multiple players means easier stamina management and less disrupted damage output as only one player really has to commit to evasion.

The logistical stuff that you lose from not having other players just makes solo into what is essentially the same game but slower.