Hi Peter,
I have a couple of commercial systems here that deal with odds on horses at their last .
Will see if I can find them.
I can post them here or you can contact me personally at hotmail.
I never really tested them myself so cant tell you if they are rubbish or not.
Their a few years old and no longer sold so no problems there.

An idea worth pursuing might be

odds on LS within 14 days

Ran 2nd or 3rd within 2 lengths

On pace runner or leader

Same class or drop in class (not up more than 3 kg in weight-Look at LIMIT weight AND take apprentice allowance in consideration -spelt LIM in your sportsman)

Todays jockey = senior jockey to 1.5 apptc

Official Handicappers weight 55 KG +

All simple stuff really and often the best.

Cheers.
darky