Dr Ron.
When working out your market and making an offer on BF, why don't you put in ridiculous odds that you want. (You say you can accept $5, why not put in $10). As the race draws nearer, lower them until you get to the minimum of your 90% market.

You would be surprised at the value you can get by having your offer on the table.
I have seen in 2 consecutive days, a $2000 bet on a horse at $1.6. The horse started at about 20 to 1. (Obviously not good for the punter, but imagine the party the layer had after that...).. And a $2000 bet at $1.10 on a horse that started at 50 to 1.

You won't get them all matched but I can guarantee you that some of them will be matched and your 90% market is suddenly 85%.