Then again, a remote electrically controlled hydraulic tyre carrier. I can't think of anything that screems British more. Just be sure to paint it BRG.
Wouldn't a heavy duty draw slide work better? This way it would stay straight up and have better mounting. The slides I'm thinking of have three pieces and extend to twice there closed length. Something about 4" wide would be enough and usually these can slide apart completely with just a lever...
I don't quite understand what you have planned but I can't imagine a weaker point of attachment than that pintle point. Slee sells the hardware to build your own swing away carrier. I have a 35" on mine with no problems. I do however have a Kaymar and am not clever enough to make my own,
Rick