SpaceX floating launch platform, for the BFR

" ...Elon is thinking of launching BFR from a floating platform."

I have only heard of this a few times, never heard it from him., though in some publications the new version is described as coming up from a floating platform, though there's only a cloud layer visible under it.

It makes sense.
I've heard of a repurposed oil platform, as the drone landing ship was repurposed vessels. Whether that is true or no, it has to evolve to making sense of using advantage or launching from the equator, even for a big rocket.
Note that 2 platforms or the rig and a bigger drone ship helps, since a booster gains even more advantage if it doesn't have to fly back, but can land down-range.

It's pretty obvious that when landing a stage or anytime a booster or upper stage is fueled or being landed, nothing can be on the platform.Remember AMOS-6 fueling test or their R.U.D. landing attempts. and scale it up to a BFR... I don't doubt the platform could be made to survive, but everything topside or exposed on the freeboard would be trashed.
The Blue Marlin or such a semi-submersible is big, and costly. An old concrete drilling platform is about right. The question is whether the rig and rocket is brought back to port for readying, or it's left at sea while the booster itself is ferried out to it, ready to be erected and fueled? IDK whether that would be easier than doing the readying and stacking at sea.