Welcome to the ball-python.net forums!
Maybe this should go in the do-it-yourself forum. Are you handy with tools? Do you have basic tools?
Screen clips and heavy weights do not reassure me. When I was starting out, I went the heavy weight route with a bullsnake. About 5 am one morning, my mother got me out of bed to catch that snake. He was on my father's tie rack in my parents' bedroom. Good thing neither was phobic about snakes. My grandmother was phobic, but that's a different story.
Most secure way I ever fastened down an aquarium lid was with metal shipping tape. I dumpster dived for the tape. Then I wrapped the tape all the way around the aquarium the long way, overlapped the ends, drilled holes in the overlap and put a small bolt with wingnut though the holes. I could lift the whole aquarium by the top with that tape holding them together.
By the way, I prefer 1/4 inch pegboard over screen for a top.
Good luck.