I’ve done it a lot, and I’ve seen a lot of shows that were not much more than that.
I would prep backing tracks (or just play your Reason session) and settle on what parts you want to play live. When I did this I was the guitar player and singer, and my cohort would press play on the laptop and do his thing. It was sort of lame but no one cares; if you are a good performer/they are entertained then don’t worry about it. Your only other option is to get a band together.
If you don’t want to use a laptop you could load up one of those little stereo or multitrack recorders with stems, or even an old iPod/etc. Some looper pedals even would work.
I would probably not over complicate things by trying to run vocals live through FX within Reason, potential for latency and problems. If you need live vocal FX, i would get a dedicated vocal pedal...or an older Line 6 pod (some have mic inputs) would work very well.
Any competent venue should know what to do with a computer setup, but I would recommend just getting a pair of cheap direct boxes to be safe.