Wheel camber and offset

I think my camber is within spec but visually it sure looks like my rear wheels have a lot of negative camber dialed in. I don't have the proper testing equipment so here is my redneck stooge best.
Cheap dial angle finder on flat wood pressed against the wheel yields a 1.5*~ negative chamber. Visually it sure looks like more although my wheels have been wearing evenly for the past 5K miles.

I'm trying to figure offset for aftermarket wheels and it looks like I can get another 21mm to get the wheel perfectly flush with the outside fenders on the rear and I could actually get the same on the fronts. I might have to roll the fender lip.
Does this amount correspond to what anyone else has done via wheel spacers or wheels. I've found some post with 15mm spacers but my measurements seem to support 20mm +-1.

1) The first picture is of the almost -2 degrees on the gauge.

2) Is of a level sitting almost flush against the lower part of the wheel and hitting the fender for reference of angle.

3) Is of a metal ruler spaced 21mm from the edge of the wheel evenly, you can see that it is directly flush with the fender.

4) Is of the front wheel and fender.
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Then I should be spot on... It just looks like more to the naked eye.