There are two free GTA demos available on official site: https://www.rockstargames.com/gta/extras/demos.html

First demo "Hot Bitch Teaser"; there are three versions for different softwares. This demo icludes Gangsta Bang level with four phone missions. You have only six minutes for playing, level ends when timer runs out. Moreover, you can reach target score using car stacking and make sure that level passing is impossible thing, because red marker won't appear. So we can easily forget about that demo.

And second demo - ECTS Competition Version. It's actually San Andreas Tequila Slammer level with timed and a bit changed Phone 3 Mission 1. Demo ends after mission completing. It would be nice to see that category in misc section at full-game leaderboards.

It's hard to run this version on modern PC's, so here you can download fully working version:

https://drive.google.com/open?id=1zv3QVLGBLqaY46KwBs6zbxaffUruECUQ

Thanks zirkoni88 www.youtube.com/watch?v=oZGpR6R0qcY for help!

I'm already have a run of it.

It sounds like it would be more fitting into the GTA Extensions section. Don´t think a demo with one mission deserves to have full category for it on the main board.

Btw you should check out discord server of gta. You will get a response more quickly than here.

Ah, I guess I should've responded here, but we talked that over, with basically same suggestion