Simple Guy Looking for Simple Truck Camper (Short bed)

I dont have a camper yet. trying to figure out how big I can go without getting too close to the trailer. Also with my car generator and tools I weigh in at 6500lbs. Although I might be okay without weight distribution I prefer to use it to transfer trailer weight to the front axle and keep the ride smooth and straight as I head down the road. My trailer is 20 foot long with full 3 foot v nose.