that"s a tough spot, and I don"t know the "right" answer.
From my own perspective, having bet it all the way and put so much of my stack in the pot already, there"s no way I would check it down on 7th knowing I couldn"t win the pot, and only leaving myself with one Big Bet. You are right that Mair shouldn"t fold if you bet 7th as she would be getting nearly 8:1 for her two pair...... BUT there is a chance she might fold having missed her full house believing you to have the flush. I would prefer to go for that small chance of her folding rather than giving it up and being impossibly short stacked afterward.
Better to go out fighting in 5th place, than limp out in 5th place two hands later...... and you never know, she might fold and suddenly you have a decent stack of 8 Big Bets.
Gotta follow through and the stick it in on 7th.