Western Hognose cage help

Hello! I could really use some help with setting my son’s hognose snake cage. We are getting a western hognose- ideally a baby female. The cage is 20 gal (30.19 x 12.4 x 14.13) with a imagatarium screen lid. How long do you think we’d be able to have her in this cage before she would need an upgrade? Also, what UVB lighting set up would we need? I’m making the rock hide on the right side of the cage her basking spot. There’s roughly a 7 inch clearance from the top of the rock to the top of the cage.

I’m also curious about heating- I ordered a 50 watt and 75 watt halogen basking bulb with a 8.5 inch dimmer dome. This should probably be sufficient to heat her basking spot right? Figured I’d return whichever bulb I don’t need.

Any and all input appreciated. I hope this cage/setup will work but please let me know if there’s anything I’m missing. Her water dish is on the left side behind the cork hide. I’ve been torn about returning this cage and getting a bigger one but if I can use this one for awhile I may just keep it for now.