Towing an Airstream - Help me check all the boxes

[ARZ540I]

Guys

I bought my X5 back in Feb 2020 and we recently bought an airstream. I have a 800+ Mile round trip coming. Trailer dry weight is 4200 lbs with the tounge weight being 600 lbs. On the three local trips i have already taken the X5 performed excellently (Well to my knowledge anyway) as i have never pulled anything prior to this. Anyway.....

The below is the current set up i have the the 35d. Is there anything else i should be considering or should pay particular attention too?

x35d, Stage 2 car - Appears to handle the Airstream without issue and no notiticable stress upon the engine, No major sway or inbalance from the rear end, It does have self leveling due to the 3rd row option, Gearing likes to drop down when attempting steaper grades but nothing i would consider out of the ordinary.

The Airstream dry weight of 4200 but of course tounge is 600 and close to the limit of the X5. The double propan tanks on the front the the trailer are @ 25% capacity and i wont be filling them until i reach my destination 400+ Miles away.

Trailer is a double axel 23ft with Prodgidy RF brake controller.

New tires all round, New Good Sam membership for roadside assistance if needed.

Figure the trailer will be 4300 lbs loaded with clothes and Food, 2+2 + Dog in the x5, 550-600 Pounds there so i'm nearing the 5000 lbs mark.

What else should i be considering here? My brakes feel good and strong, With the trailer brakes i feel confident in the stopping ability. The trip generally doesnt have many step grades to climb or decend from, I will mostly be taking I5 down from Seattle to Eugene then cutting accross to PCH into south Oregon.

Plenty of post out there about the X5 towing ability and shortfalls. I have read tons of them, I think i am ok but just being extra cautious.

Welcome any feedback
Thanks