This equipment has several bolts located near the floor I would put an angle bracket under the head of the bolt and fit a coach bolt from underneath up through the bracket and attach with a washer and a shake-resistant nut.
You cut a recess for the bolt-head by drilling part way through the bottom sheet with a spade bit.
Else tee-nuts for wood are a good option too, come downwards with a length of all-thread, glue it to stop it from shaking loose and then tighten down with a nut.
