We keep our trash in small bags liek Tory mentioned and take it with us. When we go into town for supplies, we’ll toss a bag in the can at a gas station or grocery store if we’re already buying fuel or shopping there. A lot of public parks, rest stops, and transfer stations also have trash bins.
We try to limit the amount of trash we generate by repackaging groceries ahead of time, using reusable containers, and avoiding anything with bulky packaging. That alone makes a big difference.