Sorry to hear about that. Glad you're OK, and you got it back to the hill before it took on too much water. Like you said, now's the time to do that modification to your hull, and hopefully that will eliminate the issues with cavitation.
I've had a few incidents with jetboats myself. When I owned a Sea Doo Speedster jetboat, I had a steering failure, due to corrosion eating through the steering control bracket on the jet pump nozzle...and since the nozzles are both connected to each other via a tie rod, if the main one fails, they both fail. When it went out, I was going about 30 MPH, doing a little serpentine driving. I yanked it left, then I yanked it to the right. Went to yank it back to the left, and it kept going right, and ramped across a shell midden. I bet I caught 3 feet of air, and probably went airborne for a good 40 feet or so, then landed in the middle of the marsh. Fortunately, it was high tide, so, I was able to paddle out of the grass. And since it was a twin engine boat, I was able to make it back to the hill, by varying the amount of throttle on the 2 engines to steer.
The other incident was with the Aluma-Jet. I skirted close to the bank of a channel, trying to give some fishermen a wide berth, and I forgot about a 2" diameter metal pipe that was partially underwater at the edge of that bank on that particular tide. I slid over it, and as it got to the transom, it caught the very back edge, and ripped a hole about 2 inches long, and about 1/2 inch wide....and it also managed to take out the steering control arm on my jet pump, once again, causing a loss of steering. I quickly plugged the hole with a rag, to stop the water. Then I had to have someone tow me back to the hill, as I had no way to steer.
Needless to say, I was pretty agitated about that pipe damaging my boat, and was determined to make that pipe the victim of my anger. Since I couldn't take a stick of dynamite and blow it into a million pieces of shrapnel (at least not without getting in serious trouble) I went back out there with my 14 foot Duracraft with a 15 merc, hooked a tow line to it, and proceeded to snatch it out. It took several running starts to get it out (I'm surprised I didn't tear out the transom) I hauled that POS pipe to the dump, and hurled it into the dumpster while uttering a few choice words that I can't repeat here. LOL
So, don't feel bad about what happened.....spend enough time running on the water, and something's bound to happen. Anyhow, keep us posted on the progress of your hull modification/repair. And again, glad to hear you made it through the incident unscathed.