I have the Cortech Sport Bags on an '07 Bonneville Black. Excellent quality, fit and finish. Enough space for two-up overnight stays if you are VERY spartan with your needs! Certainly enough room for one guy on an overnighter, unless you choose to dress like the guys in the Triumph magazine ads!.
I bought the New Bonneville mounting racks, but still didnt like the way it looked. I made an exact outline of the bags, cut a template out of 1/4" hardboard, and painted the templates Satin Black (both sides).
I then used the hardboard templates to line up exactly where I wanted the bags to sit on the bike. I then located the three holes provided by the NB rack, and drilled through the hardboard.
Using three M8 Hex head bolts, nuts and fender washers, I mounted the Hardboard onto each side (Zinc finish later sprayed satin black). I then stuck two black 2"W X 6"L Velcro strips across the top and bottom of each hardboard cutout, and matching strips of velcro on the insides of the bag foam pads.
Now, I throw the bags over the seat so they are easily removable (this is the only drawback, IMHO, of installing the connecting straps under the seat) and press the velcro strips together for more security.
The tops of the bags are exactly level, and in line horizontally with the top of the seat. No "bag-sag" either. They sit even with the top of the seat, just behind the shocks, with the triangular tip just about 1'4" forward of the directional signal chrome housing.
Were I to do this over again - which I probably will - I would use 1/4" Black Lexan Plastic for the templates. More waterproof and durable, albeit more expensive.
I like the end result, very stable and straight, and my wife can pillion without fumbling around with the bags for leg clearance. Lastly, absolutely no possible way for the bags to come in contact with the spokes, or shocks.
Build time was about three hours on a Saturday morning. Need a power hand held scroll saw, but I guess you could do it with a manual coping saw.

__________________
Bob

"If you're not part of the solution, you're part of the problem".