Weight and size of a game can vary greatly, too. A 1980s-era Williams is pretty easily managed with two people carrying (especially since the backbox is normally removed for transport). A widebody Bally/Williams WPC is a tank, much more difficult and pretty much requires a dolly. You can remove the backbox on a WPC game, but that only saves you about 50 lbs. The only real benefit is that you are making the game narrower by doing so, which can make negotiating the turns and doorways easier.

The turns can be managed to an extent by standing the game up on end (normally there are feet there, the games are designed to be transported this way) and getting things lined up for the next ascent.

Since you'd have to unplug pretty much everything to remove the backbox, it will probably not require much additional work to remove the playfield at that point. Then it should be quite manageable for two people. Just make sure all of your connectors are labelled first!