A jack is best for adjusting. without a jack and with only one person, it would be very difficult to do. BTW, 202 lbs is shipping weight with the huge crate. The bumper is only about 115lbs, but still a big handful for one person. I can do it by myself with a floor jack, but that is definitely not recommended!
Put the jack here:

Get one side at the right height with the jack, tighten the bolts on the SIDE ONLY (not the one on the end) just enough to keep it from slipping down. Line up other side with the jack, tighten side bolts snug. You will now likely have to go back and tweak the side you did first a little bit one last time.
Tighten the two bolts on both sides fully.
Tighten the bolts on the ends fully. Dont do the ones on the ends until the sides are tight.
That's it. If you still have problems, call me. 877-474-7625
Jim