Before I outgrew my 1.75, 2.00 and 2.25 diam tubes, all of which were about 9.0+ inches long, i was using a 2.25 stuffed, and would literally pull upward with all my strength trying to stretch and cause the ligaments to extend.
Once I got too long and the tip started to get sucked into the air outlet I tried using a section at the base of hollowed out swim float tube to give me more space, the plastic foam could not take my 8.5 base girth and split everytime.
I just purchased a 2..25 x 12.0 to continue that effort - I believe it will work.
BJ