Tip: After editing your overworld, make sure to use an EMPTY save file, as save files with progress may load Mario's position based on previous versions of the overworld. Note that altered level flags will also only take effect on new save files.
Tested with: Lunar Magic 3.11, asar 1.71, SA-1 1.32, UberASM Tool 1.4, bsnes+ v04. Works correctly, so accepted. A kind of niche patch that could turn out useful for more advanced users who wish to have more free ram at their disposal.
During moderation I made the patch compatible with UberASM Tool and added the readme file (make sure to follow its instructions if you're using UberASM Tool, or the game will get stuck upon loading!).