An onward ticket or a return ticket have the same effect. Immigration aren't bothered where you go afterwards. Don't give out partial or confusing advice. It helps no one.
If you live in Bangkok, maybe. If you don't it sounds like major aggravation for little return or a huge loss. Stick your money in a bank, earn some interest and have no hassle.
I have entered with a 60 day TR 3 times (with a paper print of the visa) and each time I carefully check what they have stamped before I move away from the immigration counter.