Any recommendations/best practices for anchoring base cabinets and bench frames to floor and walls would be greatly appreciated. Building the benches tomorrow and planning for IKEA base cabinets.
You do need to securely tie in any cabinets to the truck.
This is to prevent them from moving around during driving on paved and rough roads, and to prevent the from becoming flying objects in the event of an accident.
Since your floor is not good plywood, and I abhor penetrating the metal floor, used good screws to fasten your stuff to the framing members of the walls.
I guess securely anchored would be sufficient. Whether it be to the floor or the walls or both.
In my current van everything is secured to the plywood floor which is bolted through existing holes in the metal floor.
I used 2" L-brackets.
I don't think securing them to both floor and walls would cause any problem due to body flex. L-brackets allow for a bit of flex.
The integrity of your cabinets is also important. If you screw the cabinet back to the wall and the back is made of 1/8 inch hardboard, in a violent accident the back would stay fixed to the wall but the sides, front and top would likely get launched. Batteries are probably best secured to the floor.