This isn't really a massive guide, more a step-by-step on new tech, when it's good, when it isn't, and what I haven't tried with it yet.

You start the game as Zerk, as soon as you enter Wave 1, swap to Survivalist, remember not to try and use molotovs wave 1 since you don't have them. The other option is to do an absolutely endless amount of resets until you start Crovel with Survivalist on a run that has Hans, but that sounds like a really boring time.

For perk talents: Heavy Weapons Training: Kaboomstick is your FP/Scrake/Boss Killer. Demo weapons damage, good. Melee Expert: Hemoclobber is your primary once you get it, this makes that work. Weapons Harness: Molotov is super effective trash clear on Normal/Hard. Live it, learn it, love it. Save for clumps of 4-5 or more, or multi-spawns. Make Things Go Boom: More collateral damage on kaboomstick, less suicide by hemoclobber. Madman: Whatever, Zed time perks on this loadout almost never actually matter, but this is slightly less boring.

Now, I have NOT had time yet in the two days since Kaboomstick launched to test as heavily as I'd like, but I've had a few effective runs with it in Normal/Hard Medium and Long. Haven't done anything in Suicidal or HoE, but I'm skeptical. Suicidal is a definite maybe, but you'll probably trade a bit more for Hemo ammo and armor, which kills some of the efficacy of this strat, which primarily buys itself time on the easier difficulties by having some of the safest trade routing properly.

Your ideal boss is going to be Hans, he dies stupid fast to Kaboomstick+Molotovs, you should just be able to facetank him with your massive damage resistance and extra armor. Patty as always is theoretically a faster kill on this difficulty, but these weapons are particularly trash for 1-cycling, so just don't. Next least terrible is King FP, and for Matriarch and Abomination, just expect to take some extra time.

Maps: I haven't played this on every map, but there's a bunch I never want to play it on anyways. The guideline is: If the zeds are spawning in reasonably close distance and the trade routing blows chunks, this has the potential to be faster than what you're doing already. It works well on maps like Descent, Sanitarium, Biolapse, Desolation. It's a dumpster fire on maps like Burning Paris and I haven't even wasted time thinking about Black Forest. In general if you don't need to move much to kill the next thing, and you need to free up some movement, it's probably worth a look.

On Normal Long, you're absolutely not trading more than 3 times, and could easily route for 2. After Wave 3, you should be able to afford Hemo (buy nothing else) and after wave 5, buy Kaboomstick, ammo, grenades, and some armor. You can also just get most of an autofill here.

You want to go into Hans with about 2 Grenades, you don't need to be super greedy, he's going to die fast to Kaboomstick, so just lob one at him at the start and the second time he shields, otherwise just spam shotgrenades into his face. I'm not even technically sure the molotovs are needed as long as you have the Kaboom Ammo leftover. (Note, don't get too wild with it during the run for exactly this reason, especially if you're going for the 2-trade run.)

If you shop the third time, do it at somewhere between waves 8-10, upgrade kaboom, refill.

Hard Long works similarly, but the third trade is mandatory for speed, pick a late wave when distance is good.

Note: I make no promises Kaboom doesn't get nerfed, but I doubt "New tech for a fraction of the levels and a handful of settings in speedrunning" is a specific enough "really strong new weapon" to qualify for a nerf, and frankly I expect it's only barely passable in situations like Suicidal/HoE for 6 players due to the extreme short range.

As a side note: Kaboomstick, along with being a shotgun, meaning you need to be close to hit with everything anyways, also has a fairly short max range, and the pellets actually deal impact damage prior to exploding as well. This is part of your fast kills on big zeds and Hans, so you absolutely ARE walking into melee range and giving them both barrels center mass if you want to be efficient.

Gameplay example here: