Just to close the loop, after a month off the bike to let the hole in my elbow fill in, and after leaving the dressings off for a few days it's dried up quite nicely, I felt able to get back on the horse.
I bought a pair of Race Face D30 elbow protectors in XL (as that's what the size guide said - but I'm no Popeye these days...). They fit snugly - would not want to be any smaller.
I was concerned about bunching of the fabric on the inside of the elbow as I ride with bent arms (hamster bars) and the RF pads have a lighter weight mesh in that area - and they proved to be very comfortable, and not hot and sweaty, over a couple of hours ride today (a warm day too). No fabric bunching so no impinging on the blood supply in that area. In fact, I forgot I had them on, other than where the L one was pressing on the damaged area. But OK.
I will confess though to having been very nervous for the first few miles. The SAKI is responsive (aka twitchy) and with a shiny, new 25c front tyre on damp tarmac I was far from relaxed. Anyway, all went well, the tyre has scrubbed in and normal service has been resumed.
Let's hope for no repeats after a change to Velux rim tape, new Michelin tube and new Conti Hardshell. I'll certainly be taking the tyre off occasionally now to check that rim tape.