Easy SS Earning?

[Toketsu]

Also, I'm ~lvl 42, voting means that I can only lvl up once a day.

Not for long, soon it'll be once every two days.

I suggest you kill bosses in expert mode, that gives a lot of ss. Also sell treasure bags/loot.
Make sure you don't miss moon lord/pillars if they are spawned. You could also try to find strange plants to sell dyes (or the plants).
Lastly, if you're good at building, i would suggest you to try selling things you've built.