Your 2nd paragraph is flat out wrong. The manufacturers have fleet sales that deal with businesses that buy hundreds of vehicles. Dealerships will sell to businesses that buy multiple vehicles annually. The dealerships do stock the more base trucks when they have customers for them. I spent 10 years in the auto retail business and 3 of them were managing the truck departments of 3 of them. We had ag customers that wanted more basic trucks and we stocked and sold them all the time. I will also tell you that the manufactures packaging the SLT, XLT and other upgraded trim packages came with a packaged discount deal from the manufacturer, not the dealer. I will also mention that it was pretty rare to sell trucks without power windows, power locks, and AC even in Wisconsin. Most of the farmers wanted the rubber floor of the ST or XT, but the power equipment of the SLT, XLT.
What I really suggest is you find somebody that has been selling trucks for at least 5 years or so and knows what they're talking about. Tell them what you actually want and if they don't have it can you order it. You do have to wait if you order, but that's how you get what you want very specifically. I ordered our trucks and for the 2500/3500 series I would always add tow package, limited slip differential, sliding rear window and a few other things that slip my mind (it was 25 years ago), they were all in the $100 to $300 range each, but it made a work truck unsaleable if you didn't have them.
I will agree there are scheisters in the car business and they're usually pretty transparent if you pay attention. For the most part they bounce from dealer to dealer and talk all kinds of idiocy. However the guys that actually make a living selling cars, the actual pros, know what they're doing, will treat you with respect and do the best they can for you. Now I'm going to ask you to ask yourself a question. Since you appear to be one of those people that believes car salesmen are all liars and theives, how many lies did tell them when you were buying your truck? It was pretty rare that I didn't have to ignore lies or insults selling people the first time or two. After that they found out I was a respectable person trying to make a living, just like them, and wasn't trying to "rape" them.