I don’t know much about show jumping but I’d say if you could get them front on as their clearing the jump they might have more impact.
You have the timing alright its just about getting into a good possition maybe were the spectators are in pic 5.
They both seem to be smiling in Pic 4 they must have had a clear round.. :)
These type of showjumping events are not as easy as they look, Its hard to get a good background vans cars and even people :D But look around before you start to shoot try your best to get a clean BG as possible, and watch the way they go around the course if you get in the right place you can usually get a couple from the same round coming face onto you this is where your zoom lens earns its money, failing all that get aleast one jump clear and get face on and spend the day there better to have one really good shot and a bunch of ok ones,