The problem is that it doesn't push up against the bulkhead so the rubber doesn't seal the gap
You can't use the rubber gaiter on the bottom of the steering column either because the pinion doesn't sit in the middle of the hole in the bulkhead
I'm also not sure you can just make the hole bigger because the section above seems to be double skinned
It looks a mile out to me. You'd have to make the hole much bigger in the bulkhead and then no idea how to seal it - you'd probably have to make a blanking plate or you'd have road crap coming up at your feet.
I have to say I'm a bit gutted by the way Fred worded it - as it sounded as if it was something he'd tried and tested