Looks well executed. More of a 2/3 rear bench seat than a "split" rear bench seat though, wouldn't you say? I've wanted to do something along the lines of a 60/40 split bench so the dog can have one rear window and the kid can have the other. I guess you could add the missing 1/3 seat with another set of mounting brackets if so desired.
Out of curiosity, in your 4th pic it looks like your ZJ seat back was originally a one piece unit. Given it was designed to be supported from both ends, how rigid is it now that it has been cut? I know if only one of the seat back latches is hooked on my XJ seat back, the rest of the seat back flops around pretty easily. I'd be worried that if the center seat passenger leaned back against the cut seat back that it would flex and leave them sitting crooked.