From what I’ve read any furniture will be taxed at 30%. I would try to bring only some personal items and clothing. You can buy everything in Thailand.
I just did the same thing..it wasn’t difficult but was a pain in the ass. I couldn’t prove that I would be staying in the hotel for 60 days, so I had to make a reservation to stay in an Airbnb after the hotel stay. That’s another story. My application was rejected until I sent that and my round trip flight in and out. After that I received the e-Visa approval.
Just to let you know that Thai beauty salons don’t make much money unless they are High End salons. Thai salons are a dime a dozen. But his girlfriend can make a decent living for Thailand.