I use the OM spreadsheet too.
The way I play this is with two fairly equal teams if the odds are good enough and dutch Paddy with B365 so I cover both teams. Then if one goes 2 up I can either back them for a small profit or gamble and hope the other team pulls one back for more profit. Theoretically, one team could score two, followed by the other team scoring 4, triggering both offers. Rather fanciful thinking that though.
I'm trying to get my head around how best to do this with the US tennis too:
Boyles and betway have Double Winnings as a free bet if your player loses the 1st set and wins the match
188 have Money Back Free Bet if your selection for the wins the first set but loses the match
Paddy has early payout as winner if you go two sets up.
Unibet has money back if you win first two sets then lose the match
There must be a way to stitch these together to make the most of the offers but can't quite work it out yet.