What's the issue with having the projector on the end rail?
A few (and I personally tried them).
1) the picture is not as bright overall, and the brightness varies across the table, because the light is coming onto the table at a weird angle.
2) the focus is harder to get right over the entire distance of the table, again due to the weird angle. With the Viewsonic projectors, which are the good ones, it works ok. If you get the cheaper no-name projectors from amazon, I was not able to get the whole image focused.
3) the mouse does not move naturally. The table bed becomes the "screen" for the mouse. With the projector at the end, the mouse moves funny. This makes it more difficult to interact with the software when setting up drills, navigating the software, etc.
All of the above problems are solved if you use a Viewsonic short throw projector mounted on the ceiling approximately 1 foot outside the side pocket, pointed straight down. This is the one I bought in 2019 (I bought 3 or 4 different projectors to try them, and returned the ones that didn't work). IDK if there is a replacement to it today, but to mount where I mentioned, it must be a "short throw" model.
https://www.amazon.com/gp/product/B07B7MKC22/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
If the end rail is the only option you have, it will work. Its just not anywhere as good as the short-throw option near the side pocket if you can make that location work for your setup.