I mentioned this in the R.I.P. forum a couple times. When I had to do a deep end patch last year I investigated a lot of adhesives. All the patch kits used some glue that would aggressively attack the material and curl the patch before it could be applied. At least in my case 8' deep. Found a glue by Boxer Adhesives (#100) that is a slow acting glue and seems to work quite well. Doing a patch above water definitely has its benefits. One year later no peeling of corners or other problems. Here's the link.
http://www.boxeradhesives.com/product/adhesive.html

Statement...I have no relationship with this company that I am aware of.
Al