Definatly nothing on the legs as it would make crawling and resting in position almost impossible.
Same thing for a backpack. Impossible to crawl extensively with on in thick brush. It also make you a large target, wich in airsoft get you killed more easely than in real life.
If you want something different, look at sniper in Iraq and Afghanistan. They use a lot of suspenders and chest rigs. A lot of variety. They all have in comon the fact that they allow for a confortable prone position or to be rapidly dumped to the side.
Motorized sniper, clean armor, chest rig or other rig not shown.
Note the load bearing vest over armor. The pouches on the front look slim.
For airsoft, your kit should be slim enough to fit under a ghillie suit, since most engagements are within less than 300fts. Wich is danger close in real life.