I've never used RPG Maker anything, but that sounds like it might be a bit more complicated that you might think, for several reasons. You'd probably have to expand tour ROM, by at least the amount of space normally occupied by a Save file in the SRAM. That would be the easy part. Then you'd have to take every instance in which the ROM loads data from SRAM and point that to the newly-created place in ROM instead, which in itself would probably take quite a bit of doing because a) if an entire game's worth of data is normally stored in SRAM, then the game probably draws on it often, which means you'd have to find and replace a shit-ton of "load" instructions and b) SNES usually uses 3-byte load commands (one byte for the load instruction, two-byte parameter) to load from SRAM because it can have a default data bank set, but to load from somewhere in ROM, you'll likely need a four-byte load command so as to indicate the full offset of the data being loaded - meaning you'd have to wedge four-byte commands into spaces where three-byte commands usually exist, and there would potentially be hundreds of them. That type of task would probably make a non-newbie throw up his or her hands and say "this is way too much work," and figure out something else to do instead.
Even if you did manage to do all that, you'd still have issues to deal with...
Presumably, the user-created game allows players to save their games, meaning you'd have to keep certain parts of SRAM active. And pretty much every game uses SRAM in its own way, so figuring out what parts of your save file are for the created game and what parts are for the game's save file could take a mind-numbing amount of time.
You'd likely also want to dummy-out the ability to create other new games, since the best case scenario would be that they wouldn't load right, and the worst case scenario would be that they would erase your save files for the game you put on ROM.
I hope I'm properly illustrating how difficult an undertaking I think this would be. I don't want to discourage you from getting into ROM hacking in general, but this probably isn't the best idea for a first-ever project.