Okay, I can admit the title here is a little click-bait-y because this post nor the video is truly about needing more than 200lbs of liquid propane (LP) at any one time...
Our trailer by design typically rolls with two 100lb LP tanks. When operating, we only open a single tank at a time so we can control completely emptying a specific one before switching to the other. As our predictable, regularly scheduled season winds down, and the weather starts to turn here in the Windy City, we aim to end up with both 100lb tanks being completely empty to be removed from the trailer and put into storage.
However, this year we're operating much later into the season than usual, and needed to be prepared to have adequate LP with us without unnecessarily filling our 100lb tanks. This video describes how we used a 12' LP hose with just the right connections on each end so that we could easily and quickly connect a lighter, more portable 20lb tank to our trailer at a moment's notice
Also, for what it's worth, we realize this strategy doesn't literally extend the life of the actual 100lb propane tank, but instead the overall supply of propane readily available, keeping your vending service and selling alive...