Using a series of hub gears I have an idea and I'm wondering if it's feasible.

For an upcoming recumbent cargo touring build, I wonder if I could say use an 8-speed hub gear connected directly to an identical 8-speed hub gear, or three hub gears 4*4*4, to get logically 64 gears.

What sorts of problems might there be?
I don't have any particular parts in mind regarding ratios, but does anyone do this?

Are there any good examples of how to do a high number of gears right?

The whole point of this would be to be able to drive the bike up anything from a long ridiculous 30% grade at walking pace to an easy 100km/h on a straightaway with fairing. Is that feasible using a large number of gears?
The HP Velotechnik Scorpion is available with three front chain rings, three-gear internal hub, 8-speed rear derailleur setup. This has the additional advantage that you can shift while stopped, e.g. after emergency stops or similar.

I found it rather tedious to keep the overview over which gear I'm currently in. My Velomobiel Quest has triple front, 9-speed rear derailleur and that covers enough ground for me. Walking pace is not a problem and I spin out at about 70km/h, which is already pretty hard to keep up, even with race fairing.

Depending on where you live, riding 70km/h is already pretty dangerous taking into account that trikes cannot brake too well because the rear wheel will lift off pretty quickly.