Look at a camper from the 1960's or 1970's compared to now, and you can clearly see that they were lighter as a general rule.
For one thing, truck payloads were a lot lower and the campers had to be built lighter just because of that.
No slides. No basement. No granite countertop. No exotic hardwood cabinetry. Heck, no bathrooms in many larger campers where you'd expect one these days. Very basic wood stick structure with corrugated aluminum siding. Refrigerators and holding tanks were optional. Gray water drained out on the ground.
My neighbors where I grew up had large TCs through the 70's and 80's. They'd have to buy a different/new one every couple of years because the old one would be laying on a pile in the back yard the next spring. So, I'm not sure they were very well built, especially if neglected at all.
