What I've done previously is to get the 6x1" Centaur and cut small notches on both sides (4 total per stone) to accommodate the 45deg notch on the edge pro. Accurately notching it and getting some different spring/spacers pieces work perfectly. I have lightly modified the non-stationary stone holder on my EP, though does not interfere whatsoever with using actual mounted EP style stones. I've done this to many different stones (and many strops of various material) from DMT diasharp plates, to DMT 4" interrupted 'stones' (I guess for an 'aligner system'), atoma plates, Venev 4" spyderco ceramic benchstones, and even the ole el cheapo harbor freight diamond hone plate things. All of them work well and are as accurate as your measuring tools.
Primary reason on the Venev stones was, of course, cost and also I wanted a 2000OCB to use on an EP as well as freehand. Hard to beat like $40ish for 2 grits and able use in guided or by hand. There is 3x the amount of abrasive on the Orion stones (3mm vs 1mm), but there is plenty of use in the 1mm Centaur stuff. A note on the coarser stones, I find that I tend to use a 'traditional' diamond plate for the lowest of the low grits. When I'm chewing off material with a sub-200 grit stone I want to use as few strokes as possible and not require any stone maintenance. I feel the low grit is better served on the ole electoplated 'stones', like a dmt XXC, atoma 140, gritomatic 'basic' diamond set (bonus with these is that they are only .75" wide, as opposed to the standard 1", which can be useful) or CKTG 80/140. But ultimately it comes down to personal preference and what works best for you of course.
The whole DIY guided sharpener hacking is how I got into using an EP. I was given an EP apex with one stone for free, being stubborn/lazy I just let it sit in the box for like 2 years, and I've only ever sharpened freehand for 20+ years, so I wasn't in a rush (and that's easy when you've spent exactly $0, well, I paid shipping). Planned on messing around with it at some point and primarily using it to set clean, accurate bevel angles and do mostly hand from there. Well, one thing led to another and before ya know it I'm playing a game of lets see how far we can push the DIY edgepro game (the answer is 'pretty damn far', though I caved for decent stones along the way and likely will add that multipoint guide doohicky as that cost/benefit ratio is way in favor of buying it).