Dave, I haven't gotten to the fitting out stage yet on my West River 162, but here is my plan:

Get some of that ridgid green foam that people use to make dried flower arrangements. The stuff compresses easily and remains in the shape you give it. You can get blocks of the stuff from a garden or craft center.

Use double sided tape to stick the blocks into your estimated positon of your hip braces and gently sit down on your seat. The foam should compress and give you an exact form fit. Remember, once this stuff compresses, it does not spring back. Now copy the shape in mini-cell foam and you have your perfectly shaped custom brace. Do the same with the knee braces, taping them in position, or perhaps just holding them while you crush them into shape and find their proper position with your knees.

If anyone tries this foam trick please let me know how it works out, I'll be trying it myself in a few weeks.

Will