Seua Lag Hang is usable, but like Garland's old coach mentioned, you have to be pretty dam good to pull this off. It's taught in Muay Thai Chaiya (and I'm sure it's the same base move as you've learnt in Krabi-Krabong chalambok), and there's a variety of moves from this stance, mostly to counter the kick to the head that is so tempting! Check the 'Chaiya' film, Tae does it at the beginning and counters using Hanuman Fad Goomagan to counter a drawn Teeb kick.
The simplest is to simply stand up and catch the leg, as by standing, the head level becomes waste level, and the kick is open to be caught and countered. The kneck can also be grabbed, body pivots and take the opponent down (Ben Su Men). Again, non of these are simple moves, and are very risky. When training, we practice this move, mainly to exercise our legs (any students of Baan Chang Thai will remember the pain!), but it's fun pulling it out when sparring green students, as it can really confuse
George, can you explain the Tiger Walk from the muay Korat system? Sounds interesting.