Please critique my home front-end alignment method

I know this is an older thread. I have a cheap harbor freight angle finder I was going to use to measure camber/caster using the 20 degree method. My question is, what do the real caster/camber gauges do that is different than my angle finder? Does it just eliminate the need for doing calculations? Are they more accurate? I just rebuilt my whole suspension and have the offset bushings so getting ready to tackle the alignment.

Second question since "stops" were mentioned. I notice my brake hoses are pulled pretty tight when I go full right or left. Is my "stop" missing something? Or is that bolt head really the only thing that limits it?

View attachment 1716264211
My assumption is the Longacre bubble gauge is calibrated in such a way that the multiplication factor isn't needed. If you look at it closely, the glass of the level has an arc, it isn't flat like a normal level.