I have seen that one discussed in the past. Try using the search function. The only problem with rubber and silicone parts it that they wear and tear, seriously, and you have to buy replacements, or find substitutions. Also with bungee type extenders, how do you know what tension your applying, and consider that the tension depends on the position of your leg.
And yes it should work because, simply, if you pull only using your hands then it will/should grow. No guarantees thou, there are so many factors.
Sept 2020 BPEL 16.5-17.5 cm, BPFLS 17.5-18 cm. Clamped x4+ BPEL 18-19 cm. Head girth 12.5 cm, MSG 16 cm, BG 16.5 to 18 cm
Goal is 21 cm BPEL, 20 cm EL, 15 cm head girth.