Get a smaller cover?
http://www.gezagear.com/- Very nice covers and very low bulk.
Hmm I guess you carry more stuff than me. I did a 4 day trip with a 25L back pack and smaller tank bag. DesmoLu and El Matador traveled from Mass back to Tx with only a camel back between them... but I bet they stunk!
Creative and organized packing can get a lot of stuff in a space as well...
But! Saddle bags - they are a universal fit item so some fiddling may be needed. They come with straps to help secure them to poins like passenger pegs etc. Being a universal item, you may need a strategically placed bungee or light webbing strap to ensure a solid fit in the event one of hte supplied/integrated straps just won't do.