Not that I endorse this, but this seems the wrong way to do this. Take one job and do well at it. Get a reputation that you don't need to be managed. Work hard. Identify a niche for work that needs to be done but is currently underserved. Take over some of that niche while telling everyone how hard it is. In reality the niche takes 20 or fewer hours a week.

Get the second job lined up. Take some vacation from the first and come out the gate hard at the second job. Attempt to more or less repeat what you did.

If you can get yourself setup on the right little niches you could probably keep three or four jobs going. If you are just kind of jelly fishing along though eventually people will notice how all the other juniors in the same surface area out perform you. You want to be the person who went off, slew some dragons in a specific area, and we need to keep this person around to ensure the dragons don't repopulate.

I basically get promoted doing that. Of course I'm using my spare hours to go help other people in the org, build relationships, get noticed, etc. All while having an easily defended core area to handle. Just do that but collect other jobs instead of promotions.