I decided to buy a wolfman beta bag - http://www.wolfmanluggage.com/Tail/BetaRearBag.html
I got mine from http://www.windingroads.co.uk/ - I exchanged a few emails with Martin from there and was given excellent advice - and that is always good to get - expert advice!
Main reason I wanted this kind of solution was due to my high cans, and keeping the centre of gravity right...
anyway, it arrived - cost including delivery was £105
took a little while to fit as there are a lot of straps - the advice frfom martin was to put stuff in the bag - that makes it a lot easier by the way.
the rear is secured with a strap around the tailsection. the front uses two straps, normally to the footrests but as i do not have those, i used the rear subframe - these tension up to keep everything tight and secure
the bag has two straps at the back and on the top allowing the very easy option of securing a tent in a bag or other items. (Tent at the rear for me, folding chair at the top!)
There are multiple bungee D ring points on the bag as well for securing just about anything else you fancy
The bag has one large central chamber - in the photos above that has an inflatable mattress in it, and a sleeping bag - I think that has used about half the space in that compartment.
The bag has two side compartments as well - generous size - I was easily able to fit a small stove with gas cylinder, canteen, cup and other cooking equipement - and there was still space left.
The quality is very good - the design is excellent and the bag has been well put together.
Only downside, and this is common to all soft luggage, it is shower proof only - ie, bin liners all round for for rainy days if you want to ensure your socks stay dry!
some poor pictures:
and
I researched this kind of luggage fairly extensively - I think for my needs, and maybe some other folks as well, this is the best tail bag out there
