Wether a piste is doable or not, besides it generall grade of difficulty, is also decided by weather elements. And thus might change quite quickly.
I should check it, but if the M7 is the one going south from Tinrhir to ... (euh can't remember and not at home) then that one is doable. For us the first part was a mud race due to heavy rain!!!! Normally it should be fine.
An other doable one is the one going over Igherm through the anti atlas. But keep in mind, you'll be in remote area and a stupid fall can have very serious consequenses.
The fact that you are on your own is the tricky part as a first timer. I solved it by hooking with other groups from time to time. Or also a trick is asking the touristy 4x4 convoys where they are heading. If they go the same way you can arrange stuff with them. It makes the thing a lot safer. I did this on the loop along the Tizi N ticha (lots of folks on this track).
You could also consider to head south to Erfoud (and have some fun under way, there are some tracks that you could include). Get to Erfoud and just hook up with a couple of other bikers or 4x4's to head out to Merzouga and play. That shouldn't be a problem.
No, I wouldn't mind if you would mail me some more questions.
Have fun planning!