I'll check for my archived photos. I do have some of underneath install. I thought you just wanted more of the Cat itself. I fudged ours lower than instructions because of the window, but the rug underneath barely heats up anyway, so all is good there. For now an install description:
Our CY had the propane line ending under the kitchen for all items...oven, range, furnace, water heater. I disconnected a couple of them, added the appropriate fittings to retain them plus adding 13.5' of 1/2" black gas pipe straight back to my ending point near the rear axle rear spring hanger.
Installed a 1/2" gas shutoff, then added proper length of that yellow-coated flexible gas line straight up thru the floor onto the Cat fitting. Secured the pipe with metal conduit straps and paid attention to moving suspension parts not interfering.
Just don't confuse my cats with the wall mounted Cat...