I'd recommend skipping Windwalker and Unhindered, light armor isn't all that heavy and you'll barely notice the difference. Use those perks to take power shot for archery, and ideally I'd say try to spare three more perks for critical shot. Or pass on archery and just focus on backstab, I almost feel like taking both one-handed and archery is spreading perks thin in redundant places.
Alchemy is so powerful, I think you'll be fine regardless of the details, potions can carry almost anything through combat and Illusion is strong enough handle most things already.
It's hard to make recommendations since I feel like the entire pickpocket, speech, lockpicking trees are a waste of perks. I can say though, that keymaster is a
total waste of a perk, as keys are the easiest thing to steal already and you really won't need any boost there. Master illusion is also a waste IMO, a dual cast pacify is better than harmony. I'd personally pass on the fear and frenzy specific perks too, pacify is the best. But that's my preference I suppose. I've also heard poisoned perk is pretty bad.
I also wouldn't plan for 80 unless you really want to grind.