..... My research tells me that even at 70 lbs the wood is more likely to break than the screw is to rip out. My room mate and I have already tested our weight on it but I'll post a pic to provide some solid evidence
Did you factor in leverage? Load strength is typically measured with gravity. When you hold the handle the edge of the tank base becomes a fulcrum point.
Good design idea to use two pipe straps. I think a full pc.of dowel rod would be stronger. Better still would be 1" black water pipe. In H.S. we couldn't afford both Barbell plates and the bars so we used Black water pipe.
It's hard to tell if you used pine or oak dowel. Oak will give mote strength. Also consider the direction of the dowel wood grain in relate ship to the fulcrum point. Think about how & why a baseball cracks when it hits a baseball.
Interesting concept, the older I get the them more moving tanks becomes a real concern. Looking forward to see how this develops.