Kevin, thank you for sharing your concern about the size of the fins. I wonder if you can elaborate on your concern, and perhaps even suggest how I might address it.
Very large fins often end up very heavy, adding weight exactly where you don't want it. They're also more prone to flutter, and finally, more prone to breaking on landing.
If you use the same motor as I did, and the same number of buckets, I suspect you're going to get more altitude (and more velocity) than I did -- I had constant transitions the entire length, which I believe created more drag. More velocity means more of a chance those big fins are going to cause a problem.
Short, squat rockets also do "funny" things in terms of stability. If you do decide to go this route, I'd suggest test flights with smaller motors, flying from far out pads, for safety reasons -- my first bucket flew on a modest K, but I flew it from the M pads, even though optimistic sims said it wouldn't go very high.
I notice that most of the feedback concentrates on the rocket. That is only half of the justification for rejecting my idea. The other half is the amount of my HPR experience, which, while possibly a useful requirement, is nowhere in the rules either, not even in a vague form like "applicant shall have sufficient HPR experience." I have less experience than a lot of people on this board and in my club. At the same time, I take offense at people calling me a one-flight-under-his-belt newbie.
Personal opinion? You're rushing through levels fairly quickly. Stop and smell the roses, and have fun along the way.
In my experience, people who go through levels quickly tend to burn out quickly, and are quickly out of the hobby.
When a TAP or L3CC doesn't know the flier personally, they have a harder time judging whether or not they think your build and/or designs kills are going to lead to a good chance of success. Without that knowledge, they're going to base it more on how long you've been at Level 2, and how many flights you've made. I suspect, based on what you've posted, that the L3CC you've talked to doesn't know you.
End of the day, it's your choice. It'll be harder to convince someone who doesn't know you that you're ready if your flight count is low. End of the day, whether or not to approve it is their choice, and you have to remember, they have to put their name on the dotted line, so they have a bit of skin in the game, too.
-Kevin