HR trainer Vs road

this may get a little long,please bare w/me.When on my trainer I can control HR,cadence,etc. very well.My base training is 2-3hrs @65%-70%MHR with tempo or high cadence trainig thrown in.My typical tempo trining is 30-60min,in 53x17@79%-82%MHR(this is so high because I have my trainer on the second highest resistance it can be).As I have planned,on the road(muscularly speaking) it is very easy to push bigger gears.I can ride all day at 20-22mph in a 53x14 without much muscle fatigue.the problem is,on the road,my HR is very high.At this speed,my HR will be 78% or so.which is ok,except when the road goes up or I need to sprint.I get into the red zone very quickly.I'll be very strong on the first couple of hills,but unless I go at 12mph or some other pathetically slow speed,I don't recover.as strong as I need to be to race,I feel I should be able to ride 25-27mph (which I am approaching) but I need to maintain 19-22mph on hills and still recover without having to go slow and get dropped after.Any training suggestions?