dude - try get hold of some old jump waterskis - they are long, relatively low rocker (as long as you got older) and are fairly wide. Years ago I tried to ski on some behind a flexifoil stacker kite thingy with handles rather than a bar. I was able to drag myself knee deep (admittedly doing figure 8's and with no idea about power stroke / wind window).
Other option is a trick ski - these are around 43 inches long, 10-11 inches wide but with no fins - unless you can waterski on one I suggest the kiting may be tough. If i get a clean wind day and slightly overpowered I am going to give my tricks ski a go. Will get a video if I do!