RGN trailer front too low if loaded

I have a semi truck and a 48 ft RGN trailer. Both have functioning air bags. Trailer is Trailking TK60MG with mechanical gooseneck.

The problem is that when the RGN trailer is loaded, the front of the bed is too low to the ground. Like just 4 inches off the ground.

My feeling on this is that something flexes and the neck bends in relation to the bed, and it "sags".

I wonder what is the proper way to address it. I thought to buy some steel wedges to insert when hooking up to the trailer,...

RGN trailer front too low if loaded

RGN trailer front too low if loaded