Looking at roof racks for my incoming 4Runner. I've narrowed it down to Prinsu, Sherpa, Victory 4x4, and UpTop Overland. They are all similar. Are accessories and mounts cross compatible between them? For example, can I use a Prinsu load panel on a Victory or UpTop rack? I presume not, since the spacing between the crossbars would need to be the same and the crossbars themselves would have to have the exact same physical mounting properties?

Another example, let's say I want the Sherpa rack, but I want to use the MaxTrax mounting panel or Rotopack panel from UpTop. Will these fit?

Or hell, what about the jerry can mounts from Front Runner?

Or do you buy a rack and then you're locked into the mounting solutions specifically from that company? Because some companies don't even offer mounting accessories. So what do you do?