Using a pickup truck bed as a vegtable planter

[mick5500]

We have a large dirt 3rd lower yard in the house we bought and there is a small pickup truck bed left behind. It is 7 feet by 4 feet and 30 inches deep.

I would like to use it as an above ground planter . What do I need to do to the steel before I put soil in it. I have it leveled and holes drilled in for drainage.
Would heavy duty Heavy-Duty Landscape Fabric be enough.
The dirt is in poor shape and I will not have enough time to work and prepare an area for this season so everything I am doing is above ground ,containers, large 30 gallon totes, 15 gallon planters, etc.

Any advice thank you