Unless I decide to live truly off grid, I guess I would not use this 8h/day, maybe 2h on average and otherwise continue to use a regular on-grid setup (which itself is already a variation of sitting, standing, and treadmill).
Do you imagine the "switching" between setups to be made simpler?
The simplest solution would be to plug your equipment into USB and AC power strips, then switch the power strip cords whenever you want to change setups.
The problem with doing this is:
1) You lose the ability to individually monitor the power consumption of each device, and
2) You'd have to use an AC inverter to power your non-USB-powered (e.g. your laptop or monitor). Using an inverter wastes a lot of energy, because you're converting from DC to AC back to DC. The more energy you waste, the less you have available to power your equipment.