There can be risk in anything of course, but I would highly recommend looking into CEFs (Closed end funds).
Many of them pay monthly dividends - many have managed distributions meaning you get paid the same amount each month for a while - and then sometimes the fund adjusts up or down depending how they are doing.
There are funds that invest in bonds, dividend stocks, do covered call writing, REITS, etc and funds that do all of the above. They trade during the day just like stocks and one thing to consider is buying ones that are trading at a discount to their NAV - meaning the market price is less then the value of the assets.
Learn about them at:
http://www.cefconnect.com/Sorter/FundSorter.aspx
A few example funds that I like would include:
HYF, DHF, SLA, IGD, ZTR, EOS
There are many that can work. Again, these can fall and you should study how they did around the Lehman crash (late 08/early 09), etc. Some fell more then others.
Anyway, I would strongly advise you to consider at least some funds like these for at least some of the money.
One more thing - as far as rental properties go, you can always hire a property management company to do all that work for you. The fee is usually around 10% of the rent. Yes, there can be expenses, but there can also be writeoffs, etc.
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