Might want to do a search for "Gryphon" They sold designs and kits.
This is what I run in. A Star Wars ATST aka the LTTC "Little Tank That Can"
The first picture is more what you are looking for. It is a VERY Flawed Design. Never built it. If you blow up the yellow box you might be able to see the weight calculations. It came too heavy for me to want to play in it.
It was designed as a two man but would carry 4 so they could be inserted deep in enemy territory, retrieve a prop, raise a flag, etc.
PVC is heavy. I calculated 2" 3" 4" pvc for the framing. It just didn't work Every PVC tank I have seen BROKE early in the game. So This is a relativly beefy design. The failures were the where the wheels mounted in the PVC. So you can see the Plywood mount for the axles in the rear. Wood frame for the casters in the front.
Look again and it is like a grocery cart. small casters in the front. Picture a gravel parking lot and trying to drive a grocey cart full of groceries across it. It won't happen. I was LUCKY enough to post this and a guy PM me and told me that he tried that and it won't work. The only way they could play in it was going backwards. His final words " There is a reason the Romans put the horses in front of the chariots."
So picture that design without the front caster wheels. Without any wheels in the front. Just sit it on the ground when you need both hands. You are the OX and you are dragging around a fancy enclosed ox cart. you have a harness around your hips to pull it and use your hand / hands to lift it up over rocks, logs, dirt birms etc. That was the leading design for a WHILE.
I wound up building the backpack mounted ATST design. The first was a frame with the "armor plate" mounted to it. The armor was polycarbonate twin wall. Cardboard made out of the stuff they make safety glasses out of. Very tough, very light. 7 pounds for a 4x8 sheet. The use it for skylights, pool enclosures, green house roofs. It takes hail and paintballs in stride.
I kept bending and breaking the frame. The armor held up. It occured to me to skip the frame. Used the polycarbonate as the structural material for the body. It worked exceedingly well. The empty shell was 15 pounds. Then added 50 pounds of paintball gear and fire power. Plays at 65 pounds.
With the success of the polycarbonate body, my thoughts turned back to this design. WHAT IF I used polycarbonate for the FRAME on this design and skipped that PVC framing all together? Would it be light enough to just plain DRAG around the field. No Wheels, No wood framing to hold the wheels. Just DRAG in around like a sled on those tank tracks.
The answer was very pleasing weight wise and the answer was YES, sort of.
As the mental designing progressed, I figured the sled tracks would take a beating. Would have to built to take a lot of lateral stress while turning. Kevlar cloth epoxied on the bottom of the tracks to grind off and replace. Figuring I would most like break the tracks, I want them detachable and replaceable. It would also make it a lot easier to transport and avoid buying a trailer. The detachable tracks involved plywood or aluminum mounting plates on the body and tracks. It would fit in the mini van or truck bed. And of course, I wanted a 360 degree rotating turret. Thats a lot of hard ware to haul around and decided against going their. It would have gun ports 360 degrees and a front mounted autoloading cannon with a 45 degree cone of fire. So a box on runners made out of polycarbonate. Still never built it. Having too much fun in the ATST walker.
But Now I coming up on 64 years old and there are certain realities of dragging a 65 pound backpack around a paintball field for 2 days. Time for me to think of my motoized tank. Well, I have a convenient design for a body right here. Hmmm. Make it all out of polycarbonate twin wall again. You know if the thing broke down mechanically, could I just rip the body off and make it into a walking tank? Why not? If it is too heavy, so what? Just another idea of mine that didn't work out.
Weight is WHY there are so few walking tanks out there. They show up, play a while and don't come back. Too heavy or they break them.
That polycarbonate twin wall solved the weight problem.