Bob USE is not a cable with a jacket but three individual insulated wires and all you are doing is adding one more to it. You may also see it done to A over head service to add the third leg for a three phase service.
I dont see any violations of the code articles you sugjest may be violations.
I do like the idea of getting the pocco to place transformers thrue out the big mobile home parks. But like every thing else there is usualy a cost to it. Give the money to the Electrician or to the pocco and the electrian.Or just have the pocco feed every pedistal and give you a monthly meter charge for every service.
