The enclosed picture is in "My Photos" section on "Modifications". We had our Surveyor for 3 years,(just traded in May) enjoyed it very much with many modifications.
As for the walls, they are thin, that is why the "winged" type butterfly nuts used for hanging an item on gyproc are the best. Although, they require a rather large hole to install, they are there for life and will support a ton. I would not hesitate to use this towel bar as a grab bar if necessary. But, the installation is not for the faint of heart, as you drill a large hole for a small bolt as the "winged nut" spreads in the wall, you also have to adjust the bolt length if necessary.
But, the best advice, measure three times, drill once,
I also find it best to use the type of towel bar that has round brackets to install on the wall and then the bar hangs on these brackets with a set screw under each side, these are often not the least expensive models at the Home store.