I have recently started skydiving (60 jumps to date) and have rods and screws T12 to T10 inserted three years ago. I am 49 so had to have a doctors certificate of fitness before my AFF, my doctor contacted the BPA medical advisor before signing me fit to jump. The BPA advice notes to doctors explain the possible forces involved to non skydiving doctors. I would say and it's only my opinion, if they are physically fit and comfortable to jump off a 6ft wall and are not of a generally fragile disposition, they should be fine. BUT I'd say you both need to make an informed decision - it's not a risk free sport.
NB. The only trouble I have is with flexibility - not sure how much that is attributed to a fat gut! Life without beer, now that's scary!