i like both and also have a 4th order design in mind as well. i dont think it would be too dificult to figure out the tuning of the right design. just calculate the port area of one side. multiply it by 2. and design ur box with that much port area then adjust the length to ur desired tuning which will be 35hz tuning.
I'd use the design on the right. It looks awesome and would be easier to make strong. I'm old school though, when that was known as the "Stroker" box //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif I have a lot of photos of those types of boxes in cars.
all things great take time, personally i'd take the time to do the right just cause its different, loads of shells out there all ready, take the time to calculate everything and the right could turn out amazing!