I think blending the hay is a good idea.  I also like the idea of getting some corn silage in the mix - the most bang for the buck feed you can get, plus you pay yourself well for your crop.  Get a tub grinder in (not a bale processor) and alternate the bales - it works the best to do either a months worth at a time or an hours grinding worth at a time (many charge by the hour with a one hour minimum).
I think you can pretty easily pay for a mixer wagon with 80 head, 40 head will be nip and tuck, but find a used one and have some mechanic skills and you'll be fine.  Perhaps you can lease one to try it out?