I am a bridge research engineer at a university. We are currently
testing a glue-laminated timber bridge constructed with 5" thick,
southern yellow pine deck panels.

When testing is complete, I'm considering using one of the panels to
construct the mother of all workbench tops. I'm thinking about a
3'x6' top which will weigh in about 375 lbs.

Questions -

What's the best way to flatten a panel? I don't have a jointer plane,
but might consider buying one for this project. I'm always looking
for an excuse to buy a new tool.

How flat is "flat enough"?

Best way to protect the top from dings?

Any body else interested in some of this material?