I try and store a years worth of gas Dave. What I’ve been running in my log splitter and other small engines except chain saws is treated 14 month old pure gas. It has been fine. I got sick of paying 2 dollars a gallon more for pure over E-10 so I’ve been buying the E-10 and treating it with a triple dose of Ethanol Shield and some Stabil that I already had. I’ve watched hours of youtube and am pretty confident that I can get about a year out of that blend. So if there is no difference other than color between HDPE gas cans and other HDPE containers it will be cheaper to just spray my water jugs red than buy new gas cans. Just painting them so I dont make a mistake and drink the gas. Prices on those regular gas cans seem kind of crazy to me now. I agree constant rotation is best but that requires a somewhat organized brain which I don’t have. Can’t tell you how many canning jars and other stored foods I’ve composted because I never rotate stock.
If your going to spray or paint the containers then go for black its the best UV protection colour make it nice and thick so light cannot get at the plastic .
Just in case the filler cap is made from another plastic like polyprop also give that a good paint as that plastic will go brittle very fast in the sun light .
Dave
One of the advantages, and there aren’t many, of being 77 is that even cheap crappy stuff will probably outlive me. 
This one falls into the ‘i heard it was possible’, but have never seen it done.
Changing a tire with a rope.
Salt water batteries?
My neighbor has just installed a PV array with battery storage. He says he has a saltwater battery.
Are these good? Can, anyone with actual experience, say anything.
Rindert
Likes a cool, even temperature. LOL. I stored a left over half case of beer in my basement one time. People I served it said it was sooooo good, they couldn’t believe it was Leinenkugel’s.
Rindert
I can’t wait until you are 79. If you think you are ornery now, about how bad you will be when you are a PRIME number… My hats off to your wife… 
The Gas should be fine in an hdpe plastic container, I would be more worried about venting, and water getting into it from the air.
You can actually curb shop small gas containers. When people switch to all electric yard tools, they put the gas can’s on the curb. Most of the time, the vents don’t work because of the weird antivent system they put on them.
We had a fuel engineer from Shell oil at one of my aviation seminars about a decade ago who stated that if you are going to store gasoline for any period of time then it should be in a metal container. The cross linked polyethylene fuel cans are actually permeable to the octane improving agents in gasoline. It is possible to loose 2 to 4 octane points per month of storage due to losses through the plastic container. Adding oil for 2 stroke engines to gasoline also lowers the octane by 2 to 4 octane points.