You need to get yourself over to Sukhumvit - Nana Plaza, Soi Cowboy, BJ bars, freelancers, massage places. All the gogo girls and freelancers will know short time hotels, often within a few metres of where you meet her.
My knowledge may be a bit old but short-time hotels used to be around 300-400B per hour hire, no ID required. Just do the deed, get out, get another girl. Repeat.
For Soi Cowboy the main one is/was to be Asoke Place on the Asoke side of Cowboy. There are/were a few inside Nana Plaza. The girl will take you to ones she knows that might be owned by the same group as her bar or where she might get a small commission. You get to know the best ones.
If you get confident, try taking girls to PB hotel a few hundred metres away. You'd have to take a taxi but I used to like the "car park" rooms (behind the curtains). Good lighting, clean enough, mirrors everywhere and er, contraptions you can use.