If you have a smaller tractor, don't need to move a lot of fuel, etc., worse comes to worst, transfer to a gallon container with a hand siphon "pump" and pour from the gallon jugs. Slow but reliable and, when I've done it that way, never spilled a drop.
I could handle 5 gallon containers but I could also dig ditches and move dirt in a wheelbarrow. But, that's why I got a tractor - to make life easier! However, if you need to move gallons and gallons of fuel and need to refill often, better find another way than a gallon at a time.
I like the idea of an elevated container and siphoning/draining directly into the tractor tank. But, I'd prefer not to get into any "dregs" at the bottom of a larger tank without a adequate pre-filter.
I find that some fuel sources are more prone to contamination that others - Including algae. (Even with a biocide.) I have tested a couple of sources and found one to be much better than my original source. Shop around.