1. The best place to get high quality straps is AW Direct (Towing equipment)
http://www.awdirect.com/
get 4 axle straps and 4 ratchet straps. Get good stuff, you don't want to lose your baby on the side of the road.
2. Never strap to the center of a front I-beam axle, you will bend it I guarantee it. One strap each side of the axle as far out to the wheel as possible.
3. Forker, you have a problem.
As far as the rear of the trailer is concerned, the D rings should be way at the far corners of the trailer. I cannot tell about the front. With your present setup, if you hit even a moderate bump, the car can hop left and right and because there is little clearance between the car and the trailer on the sides you are in for trouble. I have seen this happen. You can either move the D-rings or cross the straps.
I always cross the straps and never worry about breaking a strap since I use the highest quality from AW Direct
4. after you have driven about 5 miles get out and re-tension the straps, or at least check the tension. They tend to loosen a bit at first
I would not run straps
through the wheels; you will torque them and end up with some nasty run-out