Unfortunately with CFMOTO just entering the US market, and aftermarket manufacturers designing to the Japanese Big Four for many years (like Vortex, SW-Motech, Puig, TST Industries Womet-Tech, Woodcraft, Rizoma, GB Racing) … it will take some time to see much in the way of aftermarket bits and pieces.
I just removed the frame tube rubber plug, and the bolt head takes a 15mm socket head. Not sure of bolt size, thread, and length. I’m not going to remove it, as this bolt attaches upper part of motor to the frame (referred to as stressed member engine/frame). If removing this bolt to install a slider, I would recommend supporting the engine on a floor jack/platform of some sort, as the motor could easily drop just enough to not allow insertion of the slider bolt (same for any bike with stressed member engine/frame).
Second photo shows the end of frame bolt. Different than the Z900, which had no nut holding the bolt (bolt went directly into aluminum engine case). In my opinion, the CLX design is better. On the Z900, if you snapped that bolt... big frustration getting it out.