I guess sitting between lanes has a better chance than just changing to be honest; if two cameras get half your plate there is definitely no way they can use that; even piecing it together in the hope that it becomes readable, because as above, they're not type-certified.
...If you switch lanes you've got between one and three lanes to switch to, and in a stretch a couple of miles long there are countless cameras. I'd say you're more than likely going to be spotted by more than one camera in any given lane during that stretch, OK perhaps not consecutive ones, but you've then still got an average speed between point A and point B (or point C, D, E etc. if you will) - and if you're consistently speeding it doesn't matter whether they get your average over 200 yards or 2000, they've still got you.
There's the old favourite of finding an to snuggle up with too; but to be honest with SPECS I just don't push my luck; normally I stick to the posted limit on the button (traffic permitting), as it's only going to be a couple of miles max and I'd really rather not risk the points - the closest I've ever been was when on the way back from Ipswich in convoy with a mate of mine on his way to a gig he did in Liverpool and the needle was scratching 45 a few times in the 40 as I kept up with him - suddenly he spotted someone else's RA a blaze of red and realised he'd not updated his and relaxed it a bit though, but it was a nervous couple of weeks.
Regards,
Rob.