There are 2 types of tragic gimps ... those that are classed as a cat (e.g. B) but then choose to race in a lower cat as it's their 'recovery' ride. This should be stopped and can be easily.
Then there are those who ride below their ability, cruise, then beat everyone the last km ... not much you can really do about those unless some form of ranking is taken into account (which would bugger me up now as I've been upping my ranking in the Tiny race series
I do wonder if one way around this is to have all cats start together, in the same pens ... then everyone will need to push to the max each race just to stay in the pack .. this will force sandbaggers over cat limits by default I would think. 3R do this kind of set up.