Yes, good idea to spread it around.

If you have a credit card with a high limit or a line of credit on the existing duplex that might give you some wiggle room.

Cozy has been acquired by apartments.com, and will not let me sign up for cozy, and the functions seem limited.

The appeal of student housing to rental investors lies in its ability to provide a steady income stream, especially in areas with high enrollment growth and limited new construction.Given your experience and the quality of your properties, you should find a receptive market among rental investors.

Regarding insurance adding additional umbrella insurance is great idea. 

Quote from @Chris Magistrado: This is a terrible idea.87% of all real estate agents quit within two years.

Similar to you I was doing well in real estate, had 3 cashflowing properties as well as my primary home and then thought it would be a good idea to flip some early 1900's homes.

Another idea to consider is the FHA 203K renovation mortgage, this is another excellent tool to use because of flexibility and other worthwhile features you might consider researching.

I agree with the others here that say you need to have some skin in the game, if you are going to live there yourself, get an FHA loan rather than owner financing, you can get a 3.5% down loan, personally I do not love these as they require  PMI which is an additional expense, and you also need  bring additional funds for closing at least for taxes, title, attorney and transfer fees . borrowing from anyone else for the down payment, to include a personal loan from the bank is not a good idea, those again will be higher int. rate.

I limited each season to 20 people.