Possibility of picking up a piece of furniture locally and just using it? an old student desk can work as a decent workbench.
Alternately, make a torsion box out of a cut up sheet of plywood, laminate a work surface onto the top of it and then make a base to secure it to.
I’ll admit that I’ve given up on the idea of a wooden workbench in favor of a lightweight folding one: https://www.homedepot.com/p/Keter-21-65-in-x-33-46-in-x-29-7-in-Folding-Work-Table-197283/203118732 (but I’m constrained by having to work out on the back deck or off the tailgate of my truck)