If you think you are up to the job, you can do pop up camper modifications yourself and end up with a nice looking camper.
If you have a popup camper and see that you need it to a have a different floor plan to better accommodate your needs, you can look for modification plans that can guide you through the steps to change and remodel your camper.
If you are looking to extend the length or the height, it might become a little trickier.
You might have a 1983 with a 1984 style inside, which might not be what you want. If you need more room for handicapped access or any other reason, you can look on the internet for plans to help with modifying the interior. When you choose to do it yourself, you can save money, but you will need the time to dedicate to the project. One person in Montana last year, did not like the newer look of the interior of his newly purchased popup camper, so he decided to modify it to suit his needs. He liked an older style floor plan he had seen and decided to remodel.
I saw him later in the year at a campground in Missouri and the inside was done. He had chosen a floor plan similar to a 1984 popup and remodeled the camper to fit the needs of his wife and himself. He liked his older camper floor plan so much, but needed a new camper; therefore, he modified his new camper to resemble his older camper.
The pop up camper modifications were magnificently done with pride I might add. He had restored the camper floor plan back to the year he wanted and he did most of it by himself. He and his wife are very happy with the new camper with the old floor plan they loved so much.