The stock trailer door latches on the Tamiya trailer kits have always bugged me. I messaged a gentleman on Shapeways who makes truck parts, and asked if he could design something more realistic to take their place. It took him only a few days before listing them for sale, and they are cheaper than I thought they'd be. I bought seven sets (of four handles in each set - two left-handed and two right-handed), and have installed them on the 40' container trailer. the 3-axle reefer, the box van, and the MB delivery truck. The handle has a 6mm "peg" on the rear that fits into the hole in the door for the latch, and a hinge point that fits over a 2mm rod.
Two things to consider: you have to buy a supply of 2mm rod, (I bought 10-packs of 200mm lengths from Amazon and cut them to length); and, the doors will no longer open (the 2mm rod is a straight length that runs from top rail to bottom rail). That doesn't mater to me because I'm going for a better appearance, but it might to you. You also have to drill out the holes in the doors on the box van and delivery truck to 6mm, and I used a smell tapered reamer in a drill to do this.
The listing for them is here:
https://www.shapeways.com/product/TQ...11221&li=shops
-Mike