With this thread getting so convoluted I'm not sure how much of Sy...'s questions have been fielded.

But here's my take.

Frame your market to 100%. A 20% premium ain't around these days.

If you can't get value about your top picks, even on Betfair, then offer (bad value) lays on your bottom picks.

Try to arrange it so you mainly end up green on your pets and red on your pests.

But don't back below best tote and don't lay too much higher than median tote.

If this doesn't work for you, then try to improve your ratings.