This post is like a bad academic paper - I've taken two good ideas from other people, and combined them to answer a question / need that only a small number of people would really care about. Nevertheless, I'm sharing details here so that if someone in the future googles about this they might find some value in what I've done as a reference.
I currently rent a living space that has unusually wide trim around doorways, as well as one doorway that is unusually wide where I wish to do a lot of my training. These dimensions ruled out a commercially available solution such as the Blank Slate offerings. I decided to combine a DIY pull up bar (such as this) with the suggestion from the "Brothers Crushing Anderson" on how to have an adjustable system for their Rock Prodigy Training Center (detailed here). I have essentially zero construction / fabrication skills, and was able to do this by using structural pipe and fittings from Lowe's, as well as the necessary bolts / t-nuts / wood. All of the mounting stuff I did is straight from the Anderson website. I'll just show pics here to prove it's doable.
First, I made the pull up bar to my dimensions with a 2x8 mounted on the front:
These materials are kinda heavy and maybe overkill, but as I said I lack the skills and perspective / knowledge to fabricate something lighter / simpler that I'd still trust hanging on. Like Anderson, I mounted some 1/2" wood on the back of the 2x8 to ensure that the hangboard is nice and secure with any slop. It was just the right width to allow easy removal / adjustment while still feeling secure / still enough when hanging. I'd do bike handlebar tape on the edges of the pipe where they touch the door frame. I'll likely add fabric (maybe the soft side of adhsive velcro?) to the 2x2 that presses above the door frame.
Next, I jigsawed some 1x wood to be "backings" to the hangboard, and then affixed the "garage door stops" (again from the Anderson website) using t-nuts:
My results are no doubt rougher than what the rock prodigy was able to accomplish, but I was pleasantly surprised (considering I'd never operated a jigsaw before).
Voila, I can now put these on almost anywhere I want along the 2x8; the exception is a short range where the structural pipe flanges are bolted to the 2x8 and prevent the garage door stops from nesting. Here's some pictures showing ridiculously narrow, normal, and ridiculously wide:
Nevermind the festive fall lights on the doorway.
I can also easily hang my adjustable gymnastic rings off the 2x8 for pull ups, ring rows, etc. The last step is to mount an eye bolt for a pulley system, I'll do this tonight or tomorrow.
I make no claims that this is particularly well-designed, conceived, or executed. It is heavy, but fits my needs for the moment. It was also enjoyable as a "tinkering" project.