Ed, while not the focal point of this Brulosophy exbeeriment, I am amazed at the strength of Wilsers BIAB bag. My 5G batches are usually in the range of 10# of dry grains and much heavier when fully soaked. Goodness, we are talking a pile of dry grains and obviously much more when wet. I couldn't see the top of their chain hoist but Wilser's bag seemed to have a drawstring....not sewn in loops. WOW.
Morrey,
To give you a little history, this idea of a 145 gallon BIAB w/ 285 grain bills was a little more well planned than appears. The story starts several years ago when I tested a regular 10-15 gallon bag up with 120 lbs of weights to see how strong the voile and seams actually were.
https://www.homebrewtalk.com/showthread.php?t=384445
This seemed encouraging, and I thought 50 gallon BIAB was a big deal and started to fill orders at that level. Along the way I also noticed that as batch size increased, the bags were becoming much, much larger.
Fast forward a year or so and Tommy from Pendragon contacts me and he wants to try a 145 gallon BIAB. Story below...the key again being as the batch size increases the bag size increases and becomes stronger thru increased size of the bag. The photo of Tommy doughing in the 145 G kettle doesn't do the scale justice, Tommy must be a big guy, as the bag is almost like the size of twin sheets sewed together. lol
https://www.homebrewtalk.com/showthread.php?t=483965
Regarding lifting the huge bag, Some of the bags have a bull-tape poly webbing drawstring that is 1800 lb break strength for the drawstring. Or another method is to tie the poly webbing in a loop, and cinch the bag by wrapping the loop a couple times around the gathered bag as shown here...
https://www.homebrewtalk.com/showthread.php?t=623808
Regarding handles stitched to the bag, I'm not a fan of stitched handles as the handle strapping is only as strong as the fabric it is stitched to, and poly voile is not strong enough for concentrated loads. I feel a drawstring that applies the load to the entire top of the bag is stronger and a better arrangement than four attachment points stitched to the bag....
JMO's
Regarding step mashing, I recall several years ago Brukaiser / Kal Troester did a bunch of experiments and concluded that with today's well modified malts conducting step mashes was of little to no benefit. Being a lazy, goal oriented brewer with selective hearing, I kind of shut the book on step mashing at that point.