Our trailer is permanently stocked with most things like camping clothes, bedding, cookware. For other things, I use a wire bound dollar store notebook and refer to the list I created for the medications/perishables that need to be moved to the trailer. This valuable little book also includes a checklist to follow when we break camp. There's a record of repairs too. Lists, lists, lists - but it makes life so much easier !
We have 3 baskets with handles and they are used to transport the "stuff". Makes easy work out of it for us.