500lbs+ specific suspension question

Hi, I work as a healthcare traveler and will likely be traveling across country come August. I'll have a small dualsport on a hitchrack (400lbs total) and a bunch of cargo in the back (200lbs+/-) once at my destination my 4runner will be driving around unloaded with the dualsport on the back once a week or so. Likely in another 6 months I'll be traveling back across the country with the same setup. I'm replacing all my suspension. I've purchased 5100 front and rear, I plan on getting oem coils up front set at .85". In the rear i do plan on adding airbags for the added weight. As

My 2 options are

1: bilstein 1" rear springs and let the airbags deal with added weight while traveling.

2. Eibach load leveling springs and adjust them to max height to deal with the extra weight + airbags to supplement.

Am I safe to assume that I would get the best ride and performance from the eibach+airbags while I'm traveling with 600lbs or so in the back and on the hitch?

 

Firestone airbags

 

100% airbags!