In fact I am looking for something similar, a very large reflector to create very soft light. I find most softboxes pretty expensive for what they are. Currently I use a much smaller 'reflective umbrella softbox', e.g. a reflective umbrella with some cloth on top. It works well, is very fast to setup and survived a year. But it's much too small for full body portraits. I would love to buy two of these because they are just like that, but huge and have a better quality:

My only problem is that B&H charges a fortune for orders from overseas:

SubTotal: $159.98
Duties & Tax : $85.86 (that is about twice the percentage that our government charges)
Shipping: $65.60 (nearly twice the rate of USPS Priority)
Order Total: $311.44