No worries at all , I know a few ex pats and men that bring their other half to Pattaya for a bit of fun .
I can't personally recommend any girls but surely on PA I would surely use the search section on there as few bi thai women pop up . There is one but I can't remember the name of her who is great for that kinda work you looking for she is kinda mid 30's and normally have lots of pictures of her in the photo section there . Sorry I know she used to work in soi 6 and famous banana dildo act .
Back you your question I would just go to a bar and ask or sit at the bar and see if any lady come to you . This is Thailand and you can pretty much get anything for the right price so don't be shy . If they do come always remember to buy her a lady drink and see if their any chemistry there. If you don't think there is always be polite smile and just give her a small tip for her troubles .
Saying this just a reminder for anyone else bringing a lady to most bars a ladydrink cost a bit more than our beers . Last time in a beer bar with my ex I would pay 80 baht for a beer and her barcardi breezers was 120 baht I would also check out the
http://devilsdenthailand.com/They are very open for this and all the women who work there are bi sexual so I would say this best place for hassle free and you can select the woman of your choice or even have a foursome as the prices in Thailand are good value .
I hope this helps you out and good luck