Any reason this can't be done:

[Nate R]

I'd like to have my service entrance changed.

The wires drop at the top of the roof, and come down along a soffit towards an eave. Then drop down onto a wall and go around a corner to the wall underneath that eave. Meter is there with panel just inside the house on that side.

What I'd like to do is this:

Have the meter moved to the gable side. The conduit run that the wires are in would not have to move but just be shortened. Then, install a new 100A panel inside the house on the gable side of the house.

No problem so far, right?

Legally, can the new panel for now have nothing in it but the main breaker, and another say 80A breaker feeding the existing panel? This setup is only temporary, but I'm wondering if that would pass inspection.

How does that work? If you play with the service entrance cable, of course the power company has to get involved? How do they cut power to one drop?

[Bob NH]

Have the meter moved to the gable side. The conduit run that the wires are in would not have to move but just be shortened. Then, install a new 100A panel inside the house on the gable side of the house.

No problem so far, right?

Legally, can the new panel for now have nothing in it but the main breaker, and another say 80A breaker feeding the existing panel? This setup is only temporary, but I'm wondering if that would pass inspection.
Yes. You don't even need the 80 Amp breaker if you use wire adequate for the size of the main in the old panel. The inspector never saw my temporary installation described below because it was gone before it was time to reconnect. Temporary installations are permitted during periods of construction, remodeling, and maintenance. NEC Article 590.

If you play with the service entrance cable, of course the power company has to get involved? How do they cut power to one drop?

The POCO will usually cut the wires to the drop and make them up hot after the panel installation has been approved by the inspector.

When I did mine I installed the new panel inside and fed it from the old panel. I could turn off the main to permit running the wires from old to new panel. The old main protected the wires and I just connected lugs to the bus bars in the old panel and ran 100 Amp wire (#2 Aluminum) to the new panel.

I then connected all of the circuits to the new panel so I didn't have to do it on change-over day.

Then I pre-fabricated as much as possible of the service conduit and meter assembly that would serve the new panel and installed as much as I could while maintaining power. I had my change-over order from the power company and a permit from the town.

I scheduled the change-over day with the inspector and the POCO and they told me I could cut the wire and remove the meter, which I did. I then installed the new meter socket and conduit, connected the new meter socket to the new panel, removed the old panel, and called the inspector.

The inspector approved the installation and called the POCO for a reconnect. I was back in business about 6 hours after I cut the power.