Here's my 2 cents worth.

I like the idea. I currently have 2 inchs of clearance going into my garage so any baskets that would mount above the rails is out for me.

The the right kind of webbing can be very strong. What do you think tow starps are mad out of. Like someone said earlier webbing is used for parachute rigs and when opening a chute the amount of G's put on the webbing is huge. Also climbing harnesses and helocoper sling load nets are the same and also have to be able to whithstand high load factors.

As for it holding up in the weather, and my tech rig is all webbing. Yes the webing does strech when wet, but I don't think it will be enough to let it touch the roog of the rack is it is pre streched when you put it on. Also I teach scuba, my rig has held up for year of being exposed to clorinated water as well as salt water, both of which can be very harmfull to any cloth. My rig shows no signs of deterioration, except for the color fading.

I don't think this is ment to be left on all the time. just think of the wind noise this would create. This is ment to be put up on top when its needed and taken down and stowed away when not. Used like that and it should hold up for a very long time.

As for the rings as long as stainless steel is being used they should hold up fine. Although I would rather see solid straps going front to back and side to side. Less chance of failure. the stapes should all be cross swen at every intersection of two staps. This should also make manufacturing easier. If there is a need for metal attachment points a couple D-rings could easily be added to each strap in strategic locations.

I like the idea of using loops on the cross bars, gives it a more secure attachment, and the buckles used should be fine. We use thos to hold on weight belts, and they have a cam action that prevents them from opening if the webbing is pulled. Although I would recommend using the stainless steel buckles tech divers use. The plastic kind have been known to break or fail over time. Another option for attaching it to the rails would be a steel D-ring and positively closing hook. Just lay it out so the hook and dring are not in contat with the

I like the overall design, and have been considering making something up like this. Its perfect for throwing drybags or duffe bags of camping gear, dive gear, etc up top and secured with a net. I wouldn't want to put a tire up there or anything too heavy since it is not rigidly attached to anything ant there would be some give to the webbing.

Ian, I like the idea and if you want any other suggestions I'd be more than happy to help.