The holes punched for the RCA jacks are a good fit for 1/4 panel mount, though the gauge of metal may allow flex.
Spacing on the vertical is workable, side to side not so much. The send/receive would naturally allow a conventional TRS set up, but the SUB input would have to be engineered in else-how. Maybe retaining an RCA would allow for the most versatility?
Of course, that leaves needing to mount the XLR, which is mounted on the plastic block that would be ousted with a jack change. There's also the trifling detail that while the block has a center hole for mounting, the mixer metalwork does not, so something's going to either flap or be drilled.
All in all, not an out of sight project, the depth of the 1/4" plug should be allowed for with ease, given the depth of the stock plastic mount. I'm just opting to choose my battles here.