I just spent the last 3 hours shutting up and drinking beers. I got no regrets.
Aero lowers ( at least the M4E1 lowers) have the channel for the detente and spring for the takedown pin threaded and a little set screw comes with all the Aero LPKs. So when you drop the detente in and then the spring, you cut the spring with nippers ( I left about 3 coils hanging out of the lower) and then you thread the set screw down flush. It keeps you from having to dick with the spring when you are installing/removing the end plate.
Another PSA. The Wheeler tool for installing the pivot pin. This one.
Don't waste your money. The one doubles as a roll pin set punch, but for installing the pivot pin they are a pain in the ***. I shot the detente across my shop 6 times before finally losing it and having to dig another one out of the drawer. I did finally get it, but I think the best/easiest way is the magnet trick. Insert the spring then put a small magnet on the opposing side of the pin. The detente will then stick to the pin on the other side. Stick it in, shove the pin in, done.