[CPLX]

For context I have a pilots license and have tooled around in a glider a few times as well.

Some problems with this scheme come to mind quickly but these are the first few:

1) Weather. It exists and basically makes this plan totally unworkable on any practical level.

2) Physics. An unpowered glider would have at best 1/100th the potential energy to fly distances like the ones you describe assuming perfect weather. Remember there are hard limits on altitude (due to oxygen) and speed (need to not rip the wings off) and those plus weight are the variables in your equation that tell you how far your glider can get unless it’s able to exploit unpredictable thermals.

3) Refundancy, or lack of it. The failure mode for the slightest miscalculation is certain death for your passengers and maybe a few on the ground. Unpowered flight leaves essentially no margin for error which makes it a non-starter.