for luggage i've recently bolted a pelican 1520 to my ebay bbq rack (lining up the existing 4 rack top bolts plus drilling for 1 more rear one). the whole setup is very solid. i mounted it back from the from the front edge of the bbq rack about 1" so a passenger can have more room and so i can use my other piece of luggage: giant loop coyote bag http://www.giantloopmoto.com/products/coyote-saddlebag
the coyote bag has a lower strap/hook system for use on top of a fender but also has those 2 center straps that go all the way around. if you have a rear rack or loop points you can just use those to hold the bag in place plus it also straps to the passenger foot peg mounts.
so the 2 center loops go through that gap between the front edge of the bbq rack and the pelican, strapped on the rack and held hard in place. it sits on the rear of the seat and once the 2 foot peg straps are cinched, it's rock solid on the bike yet nice and light feeling.
i was thinking about hard side bags but recently i've seen a dump in the dirt by someone else who whacked the living crap outta of his leg when the bike came down and his side box pinned him. after seeing that i decided GL is the only way for me when riding off road. unlike wolfman soft system, the GL is very narrow in width and nothing is left on the bike when i'm done with it. for day riding the pelican is all the storage is could ever need.
if i need additional carrying capacity (beyond the GL & the rear pelican) i can strap another dry bag on top of the flat pelican and yet another on top of the GL. i use, i use rox straps and strap a dry bag to the top of the pelican and place on of the bunjie nets on top of the GL so i can quickly stash something.
since the bbq rack is wider than the pelican mounted on top (i'd say 3" or so) i still get the crash protection from it being the widest rear point plus it offers me a nice hand hold when moving around the bike.
if i was going to do it over, it might use caribou's quick plate mount for pelicans (mounted to the bbq rack) so i could remove the top box and have a flat surface left for other uses. http://cariboucases.com/store/?name=...=i&item=000325
i'm happy to leave the pelican up there permanently however as it only weighs a few lbs empty if i want to ride light. i don't notice it standing up or even leaning back off my butt.
here's my bike in current form
all said and done my dr goes down the hiway very nicely and yet climb loaded of rugged colorado passes too (been over mosquito & engineer loaded on tour!). not many bikes can do all that.