Hi Max,

2kg max on each side should not be a problem, and I have done it many times with my Canyon Grail.

Because the grail has no mounts/eyelids, I find the Topeak Fork cage to be excellent. I wrapped extra tap around my folks to prevent any paint damage.

I use simple waterproof dry bags that attach to the cage. 4-8 liters should fit. Examples here: http://www.seatosummit.com/collections/dry-bags

http://www.topeak.com/global/en/product/1129-VERSACAGE

Maybe you will find this video I made helpful: http://www.youtu.be/Qh4Vy9tjXDM