Like it or not, the fans are in parallel

No, you will not get twice the thrust. "Why not?" you ask. If one of the fans is in that long duct, the losses through that long duct will reduce the thrust. The longer the duct, the greater the reduction in thrust.

Can you move the inner fan towards the back end? Make the duct as short as possible.

On "the other" site there is a GWS A10 the will launch vertically out of hand. The owner holds the A10 vertical, applies full throttle and releases it. Up it goes.

So your goal is not impossible. It is simply having a thrust to weight ratio greater than one.

But I think an unwritten rule of EDF's is as T/W~1, the $ increase dramatically.