Two-tier storage systems for trailers

A storage structure, comprising:

• a first panel being generally rectangular in shape, having four corners, and including first major rails and first minor rails, the first major rails being mutually parallel and including two first major outer rails, the first minor rails being mutually parallel and including two first minor outer rails;
• a second panel being generally rectangular in shape, having four corners, and including second major rails and second minor rails, the second major rails being mutually parallel and including two second major outer rails, the second minor rails being mutually parallel and including two second minor outer rails, the first and second panels having substantially the same overall lengths and widths;
• first spacer bars connecting the first panel to the second panel to form a first compartment therebetween, the first compartment having a first and second opposed major side and a first and second opposed minor side;
• and
• a third panel attached to the second panel such that a second compartment is formed between the third panel and the second panel, the third panel having an overall length substantially equal to those of the first and second panels, but having an overall width less than those of the first and second panels;
• wherein the first spacer bars include one non-quick-release corner spacer bar at each of the four corners of the first and second panels, the first spacer bars also including a first group of quick-release spacer bars.