Everything you wrote about alternative fuels is correct. So is the reply about filtering at least some way.
Reality is that by the time you get a good pump. (Note that the air operated harbor freight 55 gallon drum one might work for about 30 gallons in my experience.). Source barrels, metal barrels will rust and allow rain water in. Find a way to pick up used oil, transport it, unload it, filter it and then pump it into your fuel tank on the truck. How much are you actually saving time and money wise?
I purchased a dozen barrels and left several at businesses and farmers to fill up years ago. Then I put the rest into a M105 trailer to be my “fuel” trailer. The only transfer pump I ever found that worked 100 percent of the time was a simple hand crank pump type. It take a lot of effort to move oil up into another barrel 4 feet off the ground. Federal DOT rules say moving more than 50 gallons of any thing as a no no. Especially in barrels stuffed into a trailer. I kept a cargo cover over the trailer if I was on the road.
I ran 100% used motor oil for many years. Then coming back from a Texas Rally in 2014 or 2015 the truck would loose power and die unless I added 5 gallons of diesel every 40 miles or so. I discovered that the in tank fuel pump had been gummed up with a thick coating of oil and couldn’t flow anything buy light diesel down to just below 1/3 tank. I cleaned out the pump screen, drained the tank and have only run diesel since.
Just 2 weeks ago I finally finished pumping the last of my barrels dry of oil and water that leaked in and scrapping the barrels. I still have 500 gallons of clean new 15w-40 diesel oil in a plastic tote a business donated to me for removal. I plan to use it for oil, not fuel in the future. I am out of the waste motor oil world. As are most of the people who were in it with me 15 or so years ago.
Do as you wish. Just think about where will you be 10 or so years from now and at what cost?