Would someone pls tell me of any traditional marriage proposals in
Thailand and, in particular, how a prospective groom might ask a
prospective bride?s parents for their daughters hand

Here is an interesting item that I found:

http://farang.pai-nai.com/article.php/20050703044731338/print

"Most of the time it is the groom's parents who come to ask for the
bride's hand from her parents." - In the most traditional sense you
would never formally ask the bride herself to marry you, only ask the
parents.