I have worked very hard to brew the perfect hefe (for my tastes). Totally disagree about it being a beginner style, if you are someone who knows what a good hefe should taste like.
I did an interesting pitch rate experiment a while back. If your yeast is super healthy (make a fresh starter, crash and decant) then you can get a solid fermentation with as little as 1ml yeast per liter or 1tsp per gallon. This is far less than the pitch rate calculators suggest. For banana you want to abuse the yeast. Use old slurry, no starter, no aeration, and much less that you would normally use. Combine this with a warm ferment to maximise further.
That's why I said "passable". It's easy to make a wheaty, banana-laden hefe with wheat extract, old liquid yeast, no aeration, and no temp control. It'll be drinkable, and more forgiving to newb process than a Barleywine or a Helles Lager. That doesn't mean it'll be a traditional, great example of a Hefe. A true world class authentic Hefe is one of the more difficult styles to master in my opinion.
Honestly maximizing the banana I think its people's first mistake. Most of the classics I recall (Paulaner, Weihenstephaner, Hacker-Pschorr, etc), show both clove and banana, but either a relatively even balance of both, or a bit heavier on the clove. That's where I've always headed, hence the process I've indicated.
I haven't found a way apart from a careful underpitch (too little and you have ferment problems, too much and you lose banana), no aeration, acid rest, and a cool fermentation. As you said, abuse the yeast. Plus a multi-step decoction mash (acid/protein/beta/alpha/mashout, or acid/protein/alpha/mashout). I've done two step infusion mashes (acid/sacch) with a bit of added melanoidin malt and it works, but it's not as good, but sometimes time/equipment render multi step decoction impractical/impossible.
Newbs abuse yeast all the time. In this case, it's beneficial (albeit without the delicate balance of a classic). That's why I think it's a good starter beer.