I have a male who has been off feed since october. He's loosing some weight but i'm not really worried about it due to us being in the midst of the breeding season. It's possible that he wasn't eating often for you because he was stressed with the move which brought him over to his RI which brought him to his breeding season fast. It makes sense that you would have issues with feeding. If anyone asks if they should take them to the vet i always say yes. It never hurts to get a professional opinion. However, Adult BP's can live without food for up to a year, its not healthy but it happens sometimes. I would say you don't have anything to be to concerned about until breeding season is over. here are some questions to consider.
1) how often are you attempting to feed him? you said that he'll only eat mice once or twice a month but how often are you offering?
2)70 degrees is much to low for a cool side. anything bellow 75 is unhealthy, but realistically you want it to be around 80 degrees.
3) what was he being fed by the previous owner? If they were feeding live animals your going to run into resistance with feeding f/t.
cheers.