Have not seen or used one like you mention. The plastic you refer to is probably something like powder coating. As for installation, without seeing it, I would be inclined to have it welded to the trailer frame if possible, rather than bolted on, if you are going to use it to support something heavy like a generator. JMHO
2003 Ford F-350 V-10 Crew Cab 4WD Long Bed
2004 Jayco Designer Medallion 29 RLTS 5th wheel
Bill, Gayle, and Mindi (dachshund)
Retired at last !
Nothing is foolproof to a sufficiently talented fool.