Tip:
When mounting the front bumper use double-sided tape to mount the 'dog bone' rubber piece to the bumper. Put the bolts in their holes on the body, and push the bumper onto the bolts. This is much easier than putting the bolts in the car, putting the dog bone on the bolts, then fitting the bumper to the bolts -- because you can't see the holes and thus lining things up is frustrating! With the dog bones on the bumper you can line up the bolts to the holes more easily.
Luckily for me, I have a small foot stool that just fit under the bumper and acted as my other set of hands to hold the bumper up while I set the bolts in to it. I hate asking for help unless I'm desperate
Anyway, bumper is now securely on the car with the air dam and, after some more rust cleaning, the front is looking more normal