Looking at the pics, that's not a "Lippert" 5th wheel camper frame... Their frames are made of super light I-beam, and the tongues don't have the brace plates like this one, nor do they have any provisions for a gooseneck. (nor would I make anything out of one other than scrap metal...)
I see a trailer that is made of C-Channel and angle. That probably means it was either manufactured, or decently home built. It was probably a 7k GVW gooseneck car or toy hauler. As such, it would pull very nice behind a half ton pickup even at max weight, whereas a bumper tow would be a bit much, and would probably require a weight distributing hitch.
If it's got 5 lug axles, they're very likely only 3500lbs rated, but it is possible they could have been rated higher if they're older. In my experience, the higher rated axles have all had a 5 on 5-1/2" pattern. If the pattern is 5 on 4-1/2", they are for sure only 3500lb axles...
Are you building it into a tiny house? I see trailer decking from underneath, and another deck being built on top... A great way to add a bunch of unnecessary weight to a trailer, but very typical of what I've seen for tiny house builds...
If you only intend to move it once or twice, and can tow it with some caution, particularly going slow over rougher roads and not curbing it, it'll probably hold up to being a good bit overweight. With only 7-8k worth of axles, there's a really good chance it'll be overweight, since a 23' tiny house is probably going to weigh 10k or more if you build it of traditional materials and outfit it nicely... They're always heavier than the builder plans.
It's not like a 3500lb axle fails if you load it with 4000lbs, but the more you are overweight, the more likely you'll damage things if you run it over a pothole or bump fast, or curb it. And you'll be over on the tires too, so keeping the speed down would be best... I've had more than 10k on a 7k trailer before, as have most farm types... You just take it easy, and understand that if you overcook it on a rough road, you're going to be buying or straightening axles...
Good Luck!!