Approach the owners of the truck and tell that what you would hope to go and offer them a copy of the print that you want to make. As long as you ask permission a lot of people are willing to let you have access. This one would be great as described with a gelled flash in the front seat. You could also light paint with a flashlight on the outside to get some of the interesting stuff while ignoring the distractions.
I think you have a great eye for composition, just think of trying to find the cool little things that draw you in.
And for the church, definitely see if you can drop the highlights to recover some of the blown out are in the front. If not, get closer to the front and get the door/windows and focus on making them the stars of the show.