If you have to do something QUICK, how about duct tape, or something of the like that will seal off the holes temporarily going down the road until you can figure out something permanent (sheet metal, plastic sheet, etc.)???
I have found that outside air comes underneath the kitchen slide as the lower outside seal is pretty much useless. I have seen sunlight streaming under the kitchen slide inside the trailer. I got some 2 inch square foam rubber (used in a kit to seal up house window air conditioners), glued the ends together to make 1 long strip, and stuff it between the kitchen slide lower inside lip and the kitchen floor the length of the slide to seal up the air leaks. I remove the foam rubber slide seal when I move again.