I punched a 1.125" hole in the van floor, This is large enough to feed a 1/2" black pipe nipple and a rubber grommet.
The nipple goes to a T, which will feed the appliance runs.
There are 3 gas powered appliances, the H2O heater, the furnace, and the cooktop. The H2O heater will be to the left (van rear) of the elbow. The furnace will be forward of the wall frame member shown above. The cooktop will be on the passenger side of Annie, On the counter near the sliding door.
I cut the joists to run the line to the cooktop, cut a length of pipe to fit across Annie, and tried to thread it.
Unfortunately, my ancient 1/2" die's threads were munged, and I couldn't get it to bite into the pipe. So, I took a trip to the not-so-local big box, and had them cut and thread a length. Took the "plumbing expert" 2 goofed/wasted lengths before he managed to cut a proper thread.
I installed the cooktop pipe, and its cut-off valve. The pipe is strapped to pieces of ply which are VHB'd to Annie's floor.
I then installed the feeds to the heaters.
All the appliances will be fed with high pressure flared LPG rubber hose. I'll install the flare adapters when I'm ready to install the appliances. Don't want to ding the flares while doing other stuff. In the meanwhile, temporary plugs will help keep dirt out of the lines.
All the joints will be accessible by easily removable hatches under the cabinetry. The floor under and around the pipes will be insulated with expanding foam. Only the feed-through and the 2 elbows for the cooktop feed will be below my flooring. They will have access hatches as well.
Next, I installed the line from the LPG tank to the feed-through. I had earlier attached the line to the regulator assembly.
Next steps will be pressure test, flush and fill the LPG tank. Then do the water runs and resume floor insulation.