I run into a similar problem when shooting dogsports. Usually you have to camp in one spot for an event and the competitors like to see their dog doing a certain obstacle. Tyre shots are a particular favourite. It's pretty boring wading through a gallery of dogs jumping through tyres :-). Less leeway for varying angles on this obstacle too. I'll always try and set up so that I have at least two different obstacles I can shoot for each run. I expect Dave is stuck with the same thing, competitors "expect" that jump shot so it's something the photographer absolutely has to provide. The experimental fun shots have to take second place. There are a couple of things I want to try at my next outdoor trial, some wide-angle full field composites and some weave sequence shots but I know that I'll have to sacrifice one of the events to do it or at least get someone else in to help me cover the "bread and butter" shots.
This is where having a second body is invaluable. Set it up with a different lens so you can swap easily between the "bread and butter" setup and the "interest shots" setup. While I normally only carry one camera/one-two lenses for the bulk of my photography, when I'm doing an event like this I always like to have at least two bodies and four-six different lenses available so I can experiment and swap setups very quickly.
Godfrey
