I like the idea.
Introduces some progression. This will also allow people who are losing a lot, to feel like they are still getting somewhere. (Hope the game stays pretty hard) And then maybe the convoy buffs will let them beat the game on a higher difficulty.
I don't think "Complete the game on Hard" should be a condition. More like "complete the game on Normal". I just feel like Hard Difficulty should be more of a final goal, and perks should help you get there. If you already achieve the final goal to get the perk, then the perk is far less useful.
I like multiple perks more than 1 perk.