It doesn't have to be this complicated. We don't need a land value tax. The most straight forward way to make people avoid speculating is to heavily tax all non-primary residence homes. Cap the amount people can charge in rent to some %s of purchase value (incentive to have high purchase value) to and set a baseline on the taxes required and make the math for building property empire bleak (absolute destruction of th…
Landlords will figure out how to setup wash sales, or as close to a wash sale as they can legally get, or trade property between entities owned by the same real people, or engage in swapping behavior with other large holders in a cartel-like fashion, etc. Closing all the loop-holes would be difficult.
Tax the net proceeds of rental properties at 90% and slap a 100% capital gains tax on any property that is not owner-occupied. Also, simply rule out renting for huge swathes of property (especially single family homes).