Consider a Biker's Friend saddlebag. Plenty of storage to get your your 65 liters, it serves as a good backrest, AND it will stay in-line with your body and your existing trunk. That makes your entire airstream longer and less interrupted, which improves aerodynamics. And it also eliminates the drag associated with sidebags...I'm thinking of adding a little bit more luggage than my already-large, 55-liter case just for one, temporary event in July.
I'm thinking about heading up to Mansfield, OH in July and entering the Vetter Challenge just for fun. It's a power-two and three wheel fuel economy challenge, wherein folks with different bikes and trikes, scooters, etc., fueled by different fuels (so far gasoline, diesel, biodiesel, and electric) commit to a real-world fuel economy competition. The placements of the competition is done by fuel cost incurred during the event, not actual fuel amount. For instance, the electric bikes have to go by the local electric rates per kw, plus they have to add the same road tax incurred by the event organizer equal to what he incurs during the competition. The diesel / biodiesel bikes (only two with the same power train, one streamlined, one not) have to incur the higher price for diesel, but the streamlined diesel has won almost every event held over the last five years or so, even with the higher price for diesel fuel. A rider/owner with a streamlined 250 has been coming in a close second, but is coming in to this event with an all-new, streamlined design, so he may topple Fred Hayes's diesel.
Anyway, I just had a thought this morning of riding up there and throwing me and the CTX700 into the event just to show all interested parties what this 670 cc engine can achieve. During the last Vetter Challenge, an NC700X was in the competition and it finished around 70 mpg. I think, and hope, that I can do better, but in the competition, the actual fuel economy will be revealed, and it will not be based on my own, possibly erred odometer reading and other areas of possible error that one incurs in just regular, personal recording. This would be interesting for me, and I also am motivated by just wanting to publicize the CTX700 in such an event and just to see other vehicles, including the streamlined machines.
The Vetter Challenge is set up as a real-world competition at real world speeds, hard accelerations, etc. In order to qualify as a contender for the competition, one has to be able to hold four, full-size, paper bags full of groceries, fully contained in one's luggage. If the groceries fit but part of the bag or groceries are exposed, then one can still qualify, but then he or she must carry the groceries during the competition. If one's groceries fit, all contained, then he or she may remove the groceries during the competition.
I did some calculations. The groceries are said to be about a volume of around 400 cubic inches. That equates to around 65 liters. My box is around 55 liters. I'm thinking about adding some kind of luggage, maybe saddle bags, just so I can be a certified contender, even though I know I won't come even close to winning the non-streamlined, gas-powered class, because the 250s will have a huge horsepower advantage on me. But if I can ride as a qualified contender, that would be better, so I'm starting to look at something that would allow for me to hold all four bags.
Now I'm relooking at this thread more closely and appreciate all the info provided.