I dealt with this last weekend getting hit with the first snow of the season on the Western Slope of the Sierras in Hope Valley. It was only two inches and I was able to drop the top and just let it blow off on the drive but anymore than that and I would have had to do something about it.
On the issue of the lift boards "creeking" that concerned me too. My lift panels are old and dead, I am about to replace them. We were traveling with a milk crate that we are currently using as the step to get into the camper and I thought about putting it on the counter on top of the ice box so that if we had a collapse it wouldn't crush and kill us.
FWC's website says the new ones are rated to 1,000lb snow load, were the old ones (mines and 89' Fleet) rated to the same? If they are rated to 1,000 lb snow load on a roof that is about 6.5 ft by 7 ft how many inches of snow = 1,000 lb. I know it would depend on moisture content but a rough estimate of when to worry and get out and clear it off would be good to know. Don't want to be crushed in my sleep
Here's a link that may answer your questions. Note that they say one inch of water is 5.2 lb per square foot, and snow can be anywhere from 3 percent to 33 percent of that, and ice can be close to 100 percent of the water weight. Your 45.5 square foot roof that holds 1000 lbs should then be able to handle 21.98, (okay, 22) lb per square foot. That would be a little over four inches of water, or a foot of wet snow. Personally, I'd be out clearing snow long before that.
http://www.aragriculture.org/disaster/ice_snow/ice_snow_accumulation.pdf