There is no "parking brake" on the 500s. (at least on my 2017)
I transport in neutral
I use 4 ratchet straps. Two from the hitch to pads both side of the bed at the front of the truck and two from the hitch to pads on both sides of the bed at the rear. It is not going to move.
Don't know if your machine has had the warranty fix done for starting in any gear or not, if not I highly recommend it. It makes things a lot easier when you stop and kill the engine. Leave the transmission in the gear that you will use when you are ready to move again. Sometimes if you place the transmission in park when you stop and you are on an incline it is hard to get out of park and into the correct gear. The transmission will hold you unless you are on a real steep incline and you probably shouldn't have stopped there in the first place.