I do not know how long the MFL bulkheads have been available, but I do not recall seeing them during my first pass through the hobby. I simply removed all of the shelves and placed the gas bottle on the hump.
I switched to using 20mm x 125mm culture tubes for this pass through hobby. They take up significantly more space than the 100mm x 16mm culture tubes that I used to use for slants. By using 3-gallon kegs and placing the CO2 bottle outside of the refrigerator, I was able to install the top two shelves, which I use to store slanted cultures, blank slants, and sterile liquid media. I am having to rethink this strategy now that I am brewing the occasional 5-gallon batch because I have to remove one of the shelves in order to store a 5-gallon keg in the refrigerator. I am thinking about moving to a 14 or 16 cu. ft. energy star refrigerator and turning this refrigerator into a fermentation chamber. I used to own two Sanyo 95XXs, so I know that the model serves well in that capacity.