I’m not in Salesforce work but its likely this part:
"but it seems like a lot of his clients want to customize the crap out of their implementation and not do things in the prescribed manner. "
When you’re consulting your ethical duty is to inform the customer of the informed consequences of those choices (using your technical expertise). The client then says “do it anyway” or “we don’t thinks X consequence will happen/be that bad so we want it done”. Then you do it as ordered, and collect your high pay. When the consequences occur exactly as you said they would, you communicate the amount of effort (money) it will take to make it as workable as it can be now that the client chose to go down this path against your advice.
This is one of the reasons consulting is profitable. You get paid to fix the same thing multiple times. Nowhere is this unethical as long as you’re honest with the client and use your skills to warn them beforehand when they are making risky (expensive) choices.