For a temporary bench I use a folding Black&Decker Workmate with a 4'X4'X1" plywood top that has a 4"X4" block screwed to the bottom and along the edges so it can be clamped in the Workmate.
The block is grooved so it hooks in the workmate jaws and not slip. Its sturdy enough for a bench grinder or working on a set of heads. I've had 400 pds on mine on occasion.
You can't really hammer on it but it gives a good open workspace that is easily portable, folded up, it fits tight against the wall.
Try and find a older Workmate as they had heavy duty steel stampings, I seen a modern one the other day and they look cheesy and flimsy. One good double wide rolling toolbox might be all you need for everything else.
Much nicer having open spaces to work on things rather than filling it up with benches.