Mossman can make trunks to your sizes:
Mossman Trunks We have been using ours as a case but it can get very heavy, so I'm thinking of using soft bags within it and bolting it to the rack when we are touring.
I use an LED strip which I velcro to the trunk or to straps on the spare wheel when that is fitted. It's a 4/4 sport so the spare wheel obscures the built in high level light.
For long leather straps look on eBay
