Although having no personal experience to offer (now stuck in Farangland), I thought it could interest some to know more about this place. This is information I gathered from some webboard and twitter reviews (though you never know whether these reviews are genuine or "suggested" by the shop owner !)
Name : Big Hands Massage
Location : 1390 soi Chan Muang 10 - Din Daeng District - Bangkok (behind Train Night Market Ratchada)
How to get there : MRT subway to Thailand Cultural Center - exit 4 - walk along RS Tower, cross the canal and then go northward through the market ; soi Chan Muang 10 is the first soi you will cross after going out of the market (no sign, better to have a look at Google Maps before as finding one's bearings could be challenging especially at night when the market is in full swing)
Opening hours : 11.00 > 24.00
Updates and information : they have Facebook, Twitter and Line accounts (search "Big Hands Massage") - twitter and line accounts updated almost daily ; many pictures but thai language only
Prices : oil 1,5 hours 550 THB (september 2020) - minimum tip 500 for soft and 800 for hard which is rather low
Reviews summary : the shop opened in September 2020 and is kept very tidy - most rooms don't have in-room shower - 12/15 quite good-looking boys on duty - some boys in the buff from the beginning - most put emphasis on post-massage activities ("soft" or "hard", depending on boy)
All in all seems to be an interesting place worth the trouble finding one's way to check it out.