Perun moto KTM 690 Enduro/SMC Luggage rack is meant to be used with all kinds of soft luggage, of appropriate size. Also, there are predrilled holes for 1 gallon Rotopax can. Here are some examples of how I use it, you may get some ideas.
I usually use it for tools, first aid kit, documents (in upper waterproof pocket) and few snacks.
Or the other:
And some close ups:
Tools, first aid kit, documents, snacks, additional shirt, socks, underpants...
Easy to strap with great Kriega hook system, aluminium hooks pass through slots easily:
Kriega US-10 + US-5
One of my personal favourites. Its hard to believe what fits in 15 litters of capacity. US-5 bag is not tall one, so it doesn't bother me even on hard off-road, when I need to put my but as back as possible on steep downhill.
And although smaller bag is strapped over fuel cap, its very easy to refill gas, it takes 5 seconds to loosen the straps and move small bag out of the way:
1 gallon Rotopax
Just enough to get me safe out of trouble, at least in my (not so big) country.
Here is how Rotopax mount looks, without canister. I don't recommend riding with it, if canister is not attached.
And with 1 gallon canister:
1 gallon Rotopax + US-5
Extra fuel, tools, first aid kit, documents, few snacks. Thanks to its slim design, I don't even notice that US-5 is there.
And refilling is not a problem:
To be continued...