Hi Dave,
Thanks for the greeting! I'm not familiar with the Multico plate, but the Bosch item is a three-sided aluminium extrusion on which the planer forms the fourth side, with the cutter on the inside. You basically have a square-section tube, the length of the planer, with a height-adjustable bed on the inner surface opposite the cutters, to give the required thickness. The whole lot could be clamped by two clamps to a bench or similar. If you have a March - August Axminister catalogue from earlier this year, there is a picture in the planer section. It could handle stock up to 80mm wide by 70mm deep. I'not sure I could see a H & S issue with it, unless it's the fact that one of your hands could end up inside it.
Danny