Rockboots and jet fins

DIR dogma says wear jet fins with my rockboots. I'm not one to follow
dogma, but I actually like the idea of having short & wide fins to
maximize my maneuverability in the water, as I've started doing more
videography.

My problem is that jet fins don't seem to fit my size 8 rockboots at all:
the large (a faux pas in DIRland, apparently) seems too small as only my
toes really fit into the fin pocket and the strap doesn't come close to
going around my heel, and the XL has too much side to side play in the
pocket (and oddly enough I can still just barely get the strap around my
heel). Even so, the contact with my foot seems sketchy at best, since the
fin pocket is symmetrical on the top and bottom (most other fins have a
larger cut into the top of the pocket to allow the foot to go in deeper).

My question: any suggestions? I thought about getting the jet fins anyway
and cutting the top of the pocket, but this seems less than optimal. Can
anyone recommend any other traditional paddle fins along these lines?

Thanks in advance.