Well take it from someone else just getting into red tails, get a a baby!! Just picked up my girl and shes a sweety, hope you find one like this. I feel like with her being as nice as she is right now, and me handling her regularly and creating a tight relationship with her she should be the sweetest snake I own in no time. I honestly do no believe it has anything to do with the fact that boas are just temperamental, you run the luck of getting a mean snake with any species.
I see the big enclosure is the problem...If you don't want to spend an arm and a leg why not use a tub, thats what I am using until I get Boaphile enclosure.