Hi - my name is XXXXX XXXXX I'm a Real Estate litigation attorney here to assist you.
Most of these limits and restrictions are based on the individual rules and regulations of each banking institution - not a restriction by law. Thus, legally speaking, there is no limit on the number of mortgages you can get. Instead, this limit is set by the lender, and you're correct that most mortgage companies cap this at 4 (used to be 8 before the mortgage meltdown).
If you create a corporation (inc., LLC, etc.), and transfer all of the property into the name of the corporation, the lender should agree to make you 1 loan using all of the properties as security for the loan. This is done all the time with commercial properties and also with property investors who own a great deal of property for rental income.
If you want individual mortgages on each individual property, you're going to run into the same problem with the 4 mortgage limit. However, if you're willing to lump the properties together as collateral for one big loan, that is certainly do-able.
This obviously exposes all of the properties in the event that a financial hardship occurs, but that's the risk you run. However, most lenders are willing to partially release collateral as the loan balance decreases due to payment.