What you want to do is possible, but the sound won't be anywhere close and what's more important, you will probably still play as a guitarist, due to smaller scale length and lighter strings.

I know you specifically asked for other options, but everyone reading this: grab a used bass from craigslist or a pawnshop! Something like an older Peavey will do just fine. A decent instrument can be found for a hundred bucks (or less!) and you can always flip it again later.

Any guitarist should fiddle with a bass from time to time. It will make you see the known tunes from the other POV and appreciate some nuances you've never paid attention to.