How about the letters you don't pronounce that don't have a garand above them?

เกษตร

Anyone know how to pronounce that one?

Or, how about this one:

เปลา

Plao or pela?

Or this. One word or two. If it's one word does the "double ro reua" rule apply?

นครราชสีมา

IMHO there are many words in Thai (as in English) that you can only "read" if you know how to pronounce the word in the first place. "Sounding out" words based on the spelling is almost impossible.