as title - the oil rigs don't benefit from their downtime for producing enough to quickly offload to a tanker, I would like to see 'pontoon storage tanks' that can be placed alongside Oil Rigs for buffering up for faster transfer to tankers. addendum to this, it would necessitate a larger electric coverage zone to reach the now-farther-away ship loading pumps - or just integrate 1x tanker storage into the rig?

Yeah, this. Oil rigs have a tiny onboard storage, if any. They need some, and should have a decent fraction of the tanker ship.

Real life ones would have storage on it, so they can extract while, ya know, waiting for a ship to come by.

Or provide smaller ships. Smaller, more often ships would work too.

Hi, you can use https://mods.factorio.com/mod/platforms
Platform mod. With this you can build on water and if you dont need anymore just pick it up and done.

i added adjustable storage to the oil rig