On that nice heavy trailer it really won’t matter which goes first.
typically in this situation I would put the heavier of the two over the axels.
You probably already have 300 plus tounge weight empty already.
Your biggest issue will be spacing on a tilt trailer. You won’t be able to place both rigs behind the tilt seam because all the weight would be riding on the lock pin upwards. If you have one rig splitting the seam and the other on the tilt bed fully. It will be tough not tilt the bed without both on the tilt at the same time.
it looks like you could have one rig all the way forward (p500) and have enough room to use the tilt bed separately for each rig.