No, it is not legal to use.
And if this isn't really a question of is it legal, but more of "will I be allowed to...'
Rules are very clear that it is a hand-held 5-gallon container.
3.C.1 Fueling. All fueling must be done from handheld DOT-, SCCA-, or FIA-approved 5-gallon or smaller jugs or from the track’s permanent pumps.
The whole "give an inch, take an ell" applies here. If one team gets an exception, then it opens up a cascade of "well, I just want to..." from other teams.
Personal Anecdote: We ran a 100% WVO system in a car at Chuckwalla and when we were putting fuel in for the first time we may have not been in full fire gear. I noticed someone filming us from across the paddock, which made me go "Hmmm, this looks bad". One of the team members then poured some of the veggie oil straight from the jug onto her hands and rubbed it on her arms and made a gesture like she was laying out getting a tan. I walked over to the penalty box to self-report our violation, and confessed that while it's not gasoline, we are still going to treat it as such so that we cause no disruption through exception to the normal flow of the already-dangerous environment. I got a "No Shit, Spank" response.
Some in the past have claimed a medical need that they cannot lift 5 gal of fuel safely. I believe the response for that ends up being something like, "Thanks for bringing that to our attention; please get a physical from your doctor and present it to us to show us you are safe to actually get into a car and go race with us. Until then..."
Hope this helps. And also know that many places have pumps at the track. If you want a more controlled manner for fueling, you can always use those.