Reusing feed bags - Insulating the rabbit room

(View from the back of the barn. The open area is the shed that is attached to the back side. On the right, with the tin attached to the bottom, is the back wall of the barn, also the back wall of the rabbit room.)
Our barn is an old tobacco barn, its got 1" gaps between every board. Our plan is to cover the gaps with 3" boards this spring. Until then, we've got breezes blowing through.

(The area under one of the bucks cages.)
Before insulation with feed bags.

(The area under one of the bucks cages.)
After first layer of insulation with feed bags.

(The area along the back wall of the rabbit room.)
After first layer of insulation with feed bags.

I left a 2" gap from the floor to the bottom of the bag so that we're able to still get a shovel and a broom along the edge without ripping the bags down. Every other day we scrape out the rabbit poops and sweep. Our plan is to attach tin underneath the cages, at a downward angle, so that the urine & poop flows into bins that we can empty each day. So far, the extra tin that we have has gone to repairing the barn roof. We're hoping to have the cages done by spring, then we can put down a solid floor which will finish the insulating. We have ventilation fans at the far ends of the room, and the bags will come down this spring when the nigh time temps are above 40 degrees.