@Liza *****
I've seen the guarantor field on Thai visa application forms going back like more than 2 decades. However, do they really care what you write on there? Generally not. I also recall the guarantor section on Lao immigration forms as well, I'd always fill in the field with my friend's contact details, but if I didn't know anyone there, I'd write N/A or even put down a guarantor in my home country as an alternative.