[8.bit.fan]

Hi Everyone!
With the completion of my 2 recent SRAM projects(Battle of Olympus and Goonies II), I'm moving on to one of my favorites and also one that could very much use an SRAM Saving upgrade instead of the cumbersome passwords:
The Guardian Legend.

Now, right off the bat, I am already running into an issue with this one. I took a look at the ROM file in my hex editor, and quickly realized that there are no empty spaces left in it. :O

I'm still a novice when it comes to ROM hacking, can someone with more experienced help with this? Can anyone see any empty spaces in the ROM where I could write some code to make this hack happen?

Thanks in advance and any help would be much appreciated!

Cheers! 

8-bit fan

EDIT:
Forgot to add, I'm attempting this hack with RetroRain's Guardian Legend MMC3 upgrade:
http://www.romhacking.net/hacks/2553/