There was a study done locally that showed if the fence top had variations (think tree branches sticking up), a six foot fence with variation was as effective as a ten foot wire fence. Apparently the variation in height reduces the deers ability to judge where the fence is and they won't risk it. Perhaps some high strands with ribbons or pie plates that move?
If the trees aren't completely scattered around, how about a strand or two of electric, run around nose level on each tree, and connecting the trees together with insulated wire?
How about bird netting over the top? (Entanglement risk for deer might keep them out?)
As far as strengthening the wire, how about bamboo or 2x2" cut to length between the posts? Speaking from experience, T-posts alone at corners need a lot of reinforcing, i.e. bracing both ways, which is pricey.
Personally, I have never had any luck with reflective tape, moving mirrors, pie plates on deterring anything (raccoons, possums, jays).
Electric fence and netting is a different story; here, electric has worked great on pigs, and raccoons. While we have deer, they have never attempted to come near the house, probably helped by 6' chain link surrounding the homestead, and a dog or two inside a smaller area within that.
Good luck!
All the best,
Peter