I fiberglassed wood tabs to the interior of the Boler
, strategically located. These act as anchor points that I screwed our bathroom walls and cabinetry to. I used some construction adhesive to get them in place then once dried I fiberglassed them in for a more permanent bond. Pre-drill everything when you go to attach to the tabs - including drilling into the tab itself with the fixture in place - but don't use to big a bit or go so deep as to go through the shell.