Some really good points. In any market, there are “lighthouse customers”. These are the influential people (usually customers but could also be analysts) that if you get them on your side and marketing for you, others will follow. In fact, they are more effective than any sales person you can hire because they are already recognized as thought and implementation leaders in that market segment. They frequent the water holes of your target customer and they have years of credibility. Identifying THEM and cultivating them is crucial for you succeeding in your beachhead market. This is not traditional sales but rather “missionary sales” and it is a profile of a person who does not just sell what is listed in the product category, because your product is not yet mature enough to do this. They are more likely called “business development” people than “sales” even though sales is what they are doing. They are just doing the more unstructured initial sales that are establishing the market. These people are hard to find and they are often the founders and CEOs of these new companies. In fact, I forget who it is (but it is good advice) that says before you hire sales people, you need to sell it yourself for a while to figure out what works and what does not work. In this case, you will also be asking around and looking closely around to find those lighthouse customers and then close one or more of them to create some initial momentum. You are correct that it is still the same basics (DMU, DMP, … essential Steps 12 &13 and then Steps 15 onward with high clock speed). You are also correct that these people are hard to find and you will likely have to develop them. The best candidate? You as the founder. No one will care more and put in more work… and have more at stake. 

I think an important part is to understand the maturity of the market (which maps on the adoption curve—but provides a different perspective):

• Raw iron: a new market, that is not yet confirmed, so the initial products are unrefined, have very basic features and there is little competition (because of few customers). One example would be wearable activity trackers. Fitbit launched the clip-on tracker in 2008, which was a very basic pedometer (no display, no sleep tracking etc). Nike launched its first wrist tracker (the Nike Fuel) in 2012, and Fitbit followed with its first wrist tracker in 2013.
• Checklist wars: once a new market is proven to be interesting, competitors show up and the main battle is in features. Remember the bulleted list of Samsung Galaxy’s ads 10 years ago? The launch of iPhone in 2017 moved the marked from raw iron (Google Compaq iPaq or Microsoft Windows CEE PDAs) into a feature-driven market. The online banking market recently started moving from this into the next stage…
• Productivity wars: a more mature market leads to an overwhelming number of features, blocking the adoption for a more conservative majority of customers, so focusing on UX and streamlined workflows is key in this stage. Revolut disrupted the banking market because it made much easier to use mobile banking.
• Openness: in a mature market, switching costs are high and competition is fierce, so the solutions need to integrate seamlessly with customers’ other solutions. An example would be CRMs, where the battle is now on integrations and pulling in data from other customer solutions (instead of replacing them).

One other thing about personas is that they should be based on research (data), not on gut feeling. In the UX research field, a “proto-persona” is an assumption-based persona, and a “persona” must be defined from demographic/behavioral data or studies.
And I totally agree that a pre-sales process with different proto-personas will help identify those early adopters (often they might not be differentiated by demographic/behavior traits, but more from a “jobs-to-be-done” segmentation).