Forming a figure of 8 in a dyneema loop

[BelleSerene]

I may be wrong but isn't this precisely what OP is proposing? The thing they intend to do differently is to also have a short loop, presumably to facilitate lifting the MOB higher.

I'm sorry, yes it is. I hadn't warmed my glow plugs before ignition this morning.

Yes, the MOB Lifesavers which I linked to have just a single long loop, which splays out over the water when the lifejacket deploys. Where you attach it to, safely out of harm's way inside your lifejacket harness, holds up to 2 tonnes so can happily be used for the hoist. The manufacturer's metal or fabric ring at the front of the lifejacket can still be used to attach a handy billy if the victim is capable - but the critical advantage of using the long loop for the hoist is that the still-able crew on board can fish it out with a boathook without the assistance of the MOB.