After reading through this thread it is obvious to me that different vehicle owners have different application needs. The big truck guys have such large inner fender wells that are very accessible and you could stand back a few feet and spray the wheel wells with a larger sprayer. But, I just don't see that happening very well with a Corvette, especially if it has been lowered.
I think I would offer an empty larger spray bottle that could be filled with a number of different products. The customers that have the need will buy it, the ones that don't won't.
Since I own Corvettes, I like the current 16 oz size. I buy most of my stuff by the gallon and refill the 16 oz bottles. If I am going to do more than one Vette in the same day, which does not happen very often, I make sure I have two 16 oz bottles filled with DS before I get started. If I get low, I just grab the second bottle.
Rich