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It is best if you contact the factory/brand that built your trailer just to make sure you do not void your warranty.
As for tie downs, you can install D-rings that attach to the plywood flooring. Some d-rings are actually welded to the frame during installation for added strength.
I have also seen some that use long U-bolts that can be inserted through the floor and then wrap around the frame.
The type of d-ring really depends on what you plan to tie down.
I think that would be a good question for the manufacturer as well.
If we can be of further help just let us know.
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