So, before I talked a vehicle I've decided to attempt to make a jbeam carport to be smashed up etc. I have my jbeam exported and my info.json set up in the mods/unpacked directory. Issue I'm having at the moment is getting it to appear in the vehicle selection menu even though it appears in the mod manager. Only reason for this I can think of is I put "car" for vehicle type because the tutorial I was using used that and I didn't know what to put instead.
I don't have any experience with creating Props, but I would look into the jbeams for those items and try to mimic the format. In the info.json, make sure the type is "Prop."