There are three items that will kill an RV regardless of quality of build.
First is sun damage. Keep it cleaned and waxed at least once or twice a year. This will keep caulking from starting and keep a nice luster to it. Also you will notice any problems starting like cracks (seal immediately) or missing screws or bolts.
Second is roof preparation. Keep it free from holes, loose seams and reseal every few years.
Third is cleanliness inside. Vacuum the flooring, furniture and dust everything and wipe down with something like Pledge. Mop the floor with a good quality product for your floor. Use the cupboard doors softly (open gently and close gently).
Do these and your unit will last as long as you need it too - 10, 15 even 20 years.
Oh, do the maintenance on your trailer as required by MFG's schedule too.