The climax involves the hero talking all his friends into a shell game counter-con with three nearly identical horses, multiple horse trailers, and someone impersonating a police officer. It was great.

Yes! I remember High Stakes fondly, including the toys, and it held up on re-read as recently as last year. I have the vague sense that I read The Danger at some point because the character dynamics ring a bell, but almost nothing about the actual plot. I may have missed Twice Shy and that sounds fine.