I just went through the same questions. I settled on the $100 HF unit good for 1500 pounds. It took me a little over an hour to make the two angle iron brackets and a trip to the hardware store to get the fasteners. I'm happy with it, once I figured out how to get my R3T to balance correctly.
The angle iron is 2" x 2" x 1/4" and cut 2" long (wide). The hole for the bolt going through the frame lug, and upon which the bike is supported, is 1/2", but the bolt going through it is 7/16" (you'll want a little slop, and 7/16" is plenty thick enough to support the bike). The bolts holding the angle iron brackets to the frame are 5/16" with the holes slightly larger (maybe 1/16" larger). Watch your placement of these bolts because the stiffener in the lift rail might be in the way on one of them.
My bike is a Touring model and may fit a little differently. It may have a slightly narrower frame. The length of the rail on the HF lift is 13.5". My bike fits almost perfectly without the need to join the two brackets with angle or strap iron and cantalever the brackets over the edge of the lift rail. The shape of the brackets is different between the right and left side. The left side was a straight cut while the right side had to be fit around the big nut/washer just above the frame lug (a couple minutes of grinding and fitting).