For the mounting block, I'd suggest working him in small circles on the ground at a fast walk/trot away from the block, and then let him rest AT the block. That way, he'll associate the block with resting. When he takes a step, make him work again, then lead him back to the block to rest. This method has worked for me so many times. :) hope it helps!

As for trainers, I like Rick Wheat. I've been breaking/fixing horses for a year or 2 now, and love his method. He can take 99.9999 percent of horses you throw at him that're crazy, buck, bite, rear, kick, or just need a little polishing up, and make 'em look amazing. He is a western rider, and you can find some videos of him on Youtube, I believe.

I don't much care for Clinton or Pat, as they seem a bit focused on selling you things/too much groundwork for my liking. Eh, just my opinion, don't jump at my throat for it.

Have a nice day, and good luck with Rio!! <33