Look for #originalsong artists on YouTube that plays only a guitar and sings...(There's like hundreds of thousands of them) then ask them if you can remix their song.
Post your remix / remaster and the original song links here! You'll show the original song from YouTube and your remixed version from YouTube... I recommend that you don't use the same video they used, even with permission. I plan to just use a blank screen with credits on them, including how to locate the original song and artist.
I understand this could take a couple of weeks or so, because you've gotta wait for a response from them, if it's okay or not, then you've gotta do the remix / remaster...
I'm putting in my requests today...
I've done something similar before and it's pretty fun.
The main challenge will be splitting their vocal from the guitar (I use Remix from Acon Digital, but IZotope has RX Music Rebalance (which I found isn't as good as Acon Digital). There's a few other software that can do it, but those two are the best as far as my knowledge goes.
I then use Melodyne from Celemony to enhance the vocals (de-essing) (putting the singer on key) without making them sound like robots.
I also use Melodyne to create a Tempo Map of the song, import the tempo map into Reaper, then I can add bass guitar, piano, and drums (depending on song genre). Cakewalk by Bandlab can create Tempo Maps of tracks, if you drag the track UP until it turns blue, then drop it.
On finalization, I use IZotope Ozone 10 Standard & Sonible Smart Limit & Waves SSL G-Buss Compressor (Glues the music together)
If you don't mind sharing your secrets to creating a remix / remaster, let us know how you did it