Mercedes Hymer gas locker capacity b 630 (2 Viewers)

[NPea]

I am guessing the gas lockers on all the merc chassis (2003 era) will be the same or even better if someone with RHD 630 could advise. I am looking at fitting 2 x 11 kg refillable bottles but not sure if enough room for the rear bottle. I thought I had measured it but got mixed up between diameter and circumference. It is an odd shaped locker so any advice would be welcome. Currently have 13 and 7.5 in there.