Insane fuel tank thought!!

[EagleChief]

So, a little background on why this thought came to me - I'm adding a fuel tank under the bed for my LS swap. I still have the stock tank behind the seat. The plan is to remove it. But, my project is going on year 4-ish.

Here's my thought/question/discussion while laying in bed awake in the middle of the night, or when I wake up in the middle of the night and can't go back to sleep:

I wonder if I can leave the original tank behind the seat and re-plumb it to feed into the tank under the bed. Would it be possible to have the stock fuel tank as an extra supply on top of my fuel tank that is going under the bed? I know it would need a valve of some sort to restrict the flow into the lower tank. Gravity feed wouldn't have a way to shut off, as the tank is higher and would continuously feed the lower tank. Could I run a pump from the original to feed the other and then the main pump to go from there to the engine?

I know it's a dumb idea, but like I said. Sometimes I can't sleep and this is something that I pondered while laying in bed one night.