He is going to try and nose around the lid, if he could he would escape. Dont know what kind of clamps you have on the lid but at some point he will get stronger & his nose will get out of there and hurt himself. The rack systems dont use lids. Its secure from the Rack. I dont know anything about Tubs and Racks, my snakes use big enclosures and have plenty of room to explore and not get into things.
Wait to feed like everything says. Don't second guess whats been written fir a reason. If you dont follow whats already been established by those that know your always going to have issues. These snakes go months without eating.