Well Tom, it's too late to do what I did. When I built my house, I knew the sewer line was going to be a problem, and interfere with the layout and another room in the basement, so I ran it up against the foundation on the outside. The run is about 80'. In nearly 20 years, I've only ever had one problem with it, and that happened within the first year. The pipe broke because a large rock had been in the back fill, and settled on the pipe. That was an expensive lesson!
Back to your situation, I do see a possibility, but it makes the problem worse before it gets better. You could extend the pipe where the clean out is, to a point beyond the layout on the right, then just do a new clean out on the end of the extension. Then you can cover the whole mess, while preserving the access.
Out of curiosity, have you ever needed to use the clean out? If you haven't, then there's a very low probability that you ever would, but better safe than sorry. BTW, I did all my own plumbing on my house, and everything works great, with the exception of the occasional toilet clog.
I was confident enough that the system was good, that I sheet rocked over all three clean outs in that 80' run. Gravity works!
Is that plastic or cast? Plastic is easier. Maybe it doesn't matter. If you can get a male threaded piece to match the plug, then just screw it into the existing, and put the new clean out on the other end. If you could move the layout out 6" it would be perfect!
