We get delivery by truck. Also, in our area you can get delivery by barge. Both are still less than marinas but rapidly rising. Also, trucks might do the multiple boats side by side but only going to do so with one payer. Trucks have various minimums but typically at least 500 gallons and some are at 1000 gallons.
Now, one other challenge. I'm being told by a Miami captain that fuel trucks are not scheduling deliveries right now in his area except to existing customers, no new boat customers. I believe they fear shortages and want to be sure to service their fleet and wholesale customers.
Some marinas don't allow fuel trucks. In our area, most do, but collect a surcharge for one. That is based on the marina's environmental and insurance risks. Now, we've also seen in the past few years, some marinas no longer offer fuel and go strictly to truck. If people want to fuel at the dock, they must go to the marina next door.