New offset mock-up

Ok so I think I have this down, but just want to double check that I'm on the right path.

My current stock setup is 16x7 inch wheels with 260/75/16.

I'm looking around at some new wheels and tires and trying to determine how far out they will stick out and the extent of trimming.
I'm pretty set on BF Goodrich KO2's 265/75/16 so there won't be too much increase in tire size.

Looking at MB TKO wheels (8.5" wide) with -6 offset and Level 8 MK 6 (8" inch wide) which I believe is 0 offset.

If I have this offset stuff right, the TKO will push everything out roughly 2.16" and the MK6 will push everything out roughly 1.7"

So theoretically I could cut an approximate 2.36" (new offset plus slighter larger tire size) and 1.9" piece of cardboard out and tape it to my current tire and see the "rough" fit and trimming needs.

Am I on the right track here or completely off-base? Pretty new at wheel/tire calculations. Thanks!