First step in managing OOA situations is having the knowledge to PLAN gas consumption prior to the dive and then to match that to the volume of gas in one's primary cylinders. In other words, the answer is not kit but better training and dive practices.
I also would dispute your findings regarding the volume of gas needed for a controlled ascent from recreational depths... between 18 and 30 metres (60 - 100 feet). During research in which I participated, we found a volume of slightly more than 400 litres (about 14 cubic feet) was the MINIMUM that allowed for increased breathing rates, an ascent at 9 metres per minute (30 feet), a safety stop for three minutes and getting sorted on the surface. Anything holding less is not something I'd recommend.
Also, just out of interest, should there be any conflict of interest disclaimer on this review?