Once you add the taxes for other jurisdictions of government I can see taxes reaching 30% of total mortgage value. It's fairly clear to me that owning land is extremely expensive in a Georgist society that needs to generate the levels of taxation that fund current government. If land value tax replaces income tax it needs to be fairly large, taking over 20% of mortgage value for just federal costs.
Some number of homes are owned outright and no longer have mortgages so the mortgage number may be a bit misleading. If we account for this we might get to a level that suggests 10% of mortgage value in taxes federally, raising to 15% of mortgage value when accounting for other levels of government. Such numbers suggest you'd need to be able to pay for your current property with an 8-year mortgage in order to pay the Georgist taxes on it.
I think a modern society that kept existing levels of government spending would see widespread downgrades in housing quality in a Georgist society.