If we are chasing a game, or having to go long, I would be tempted to bring on e.g. Rose, to replace him at the back and let him go and play as a target man. He wins the majority of headers; just needs to be coached not to give away needless fouls, as his aerial ability and presence will create havoc in the opponents area.
Definitely need to do this as we need to get Rose up to speed and we will likely lose Osti at the end of the season, can't see Brighton releasing him for anything we can afford.