Bikepacking - a viable alternative to racks & panniers

SJS or similar will have rail adaptors to replicate the bit missing. Think you can bodge it too if you get creative at a diy store.

http://www.carradice.co.uk/products/saddle-fixing-systems

Scroll down; Carradice offer cyclo loops or a clamp that fits the saddle rails, as well as the QR clamp that turns the bagman into a bagman QR (not cheap, mind - if you're just going to use a Barley one of these is about the same price and can replace the Bagman: http://www.carradice.co.uk/products/saddle-fixing-systems/carradice-classic-saddlebag-rack )

i have a pair of the velo orange clamp on saddle loops you can have for £5 if yr in ldn.
Lemme know and I'll try n dig them out.