There's this song played on the piano which I've transferred onto Guitar Pro to be played on Guitar and Bass (with both on different clefs)... Now, I'm planning on doing a video with me playing both treble and bass parts but I only have (and can only play) the guitar.

I've (sort of) come up with two solutions(ish)...

If I tune the guitar an octave down, I should be able to play the bass parts, right? But then, it'll sound horrible and I'm not exactly sure how to tune it so low.

Or I can just transpose the bass part on Guitar Pro an octave higher and play it normally on the guitar... But would that be a bit weird?

Any help would be appreciated

PS. Sorry if this is in the wrong section...
Yeah, tuning your guitar an octave lower won't really work. Your strings will be way too loose. You can try digitally lowering your guitar an octave. Sometimes that works decent if you put it through a bass amp plugin or something. Not as good as having a real bass guitar obviously, but it might be passable.
if you tune your guitar down to c and play on a clean channel with the bass cranked you can nearly replicate a bass