Are there ways to construct other alternatives to boxes that can't bear weight for those of us who want to diminish pressure on the coccyx? Like suspending a string of band so we have a feeling feedback about depth yet that putting significant weight on it is not an option?
Tycoil,Reverse Car Strap Squats
I have used a verison of this in training. I anchor car strap to the top of the power rack and then suspend the bar from them at a determined height...parallel, below parallell, and sightly above parallell.
This show the use of Reverse Straps with Good Mornings. http://www.youtube.com/watch?v=jQBbBo9XsfQ
You can do the same thing with squats, bench press, etc.
Spud Supsension Straps are now being sold for this purpose. Spud Supspension Straps are over priced Car Straps.
Car Straps are just that, straps to tow cars with. I paid about $20 for a pair that will support about 3500 lbs.
You can purchase Car Straps from some place locally in your area or from McMaster Carr for about 1/3 the price of Spud Suspension Straps.
Here's McMaster Carr' site. http://www.mcmaster.com/#
Put "Lifting Straps" into search at the site. Concentric ONLY Training
Another training method you can perform with Car Staps or power rack is concentric only training. You drive the bar up from the bottom and then let it drop back down to the straps or power rack.
I prefer the straps because there is not noise. When yuo drop the weight down to the metal pins in a power rack, it sounds like someone's like hell. Reverse Band
I then do as Stu mentioned, I attach bands to the top of the rack and then to the bar. Thus, I the weight deloads as I lower it and the reloads as I ascend.
This method does not place as much stress on the lower back, as you mentioned.