The people who leave a mess in valleys or next to lakes are not "true wild campers" they are leaving litter just the same as the like-minded ignorant day trippers do. The day trippers leave just as much or even more mess behind because they are in greater numbers.
I am pleased you are on our side btw
We do spend a lot of money in the Lake District, we try to buy all of our gear in the shops there but they don't always have what we want and we have to buy online.
I hear what you say and about day trippers and it is all true. Like you, the authorities want to eliminate the nuisance. The easiest way is to move "campers" on and the easiest way to do that is to use the existing law. "Do you have permission? No? Move on or you're nicked" The problem is that bona fide wild campers may get caught in the crossfire. That said, I suspect if you observe the normal practice of pitching above the intake wall, arriving late, leaving early, leaving no trace, not drawing attention (might be a good idea to leave the drone behind for a while), then you will not be bothered by any action to get rid of nuisance campers. At the end of the day, the law has nor changed, just the enforcement thereof, and real wild campers are not the ones they are after.
As for spending money in the area. That is very laudable but there is nothing in the balance sheet that will differentiate your purchases from any other visitor sale. I suspect sales to wild campers and seasoned walkers are a spit in the bucket in this regard. I know I spent relatively little on new gear inside the Park as I usually had all I needed and arrived with it. I also tended to buy my consumables beforehand and never used accommodation in the Park. I think in my case the major beneficiaries was the NT whose car parks I used to justify my annual membership and the pubs I finished walks at.