Why did P2P lending get a liquidity ranking of 6? It is quite possibly the most illiquid investment option you listed. You said you rank liquidity by “difficulty level of withdrawing your money without a massive penalty”, and for Lending Club notes, it’s not only difficult and extremely time consuming to sell all of your notes in their super illiquid market, but you would have to sell your notes at large losses to hope to get others interested in buying your notes. On top of that, it is impossible to withdraw your money any other way other than just waiting for interest/principal to pay off every month until maturity in 3 to 5 years. You can’t just one day tell Lending Club “I want to quit, please give me my money back.” One can even argue that it is less difficult to sell a home (in order to “withdraw” the money invested) than to withdraw all of their money from a P2P loan portfolio because it is very possible to sell a home before 3 to 5 years.
If you happen to own a home, apartment, or office space, you have a great source for generating passive income at your fingertips. Peer-to-peer property rental site Airbnb has made it extremely easy for real estate owners to make extra money by renting out their homes to guests for short durations. If you're uncomfortable with such a model, you can also use sites like NestAway to find tenants for your property without having to deal with brokers.
If you want to top up your income without taking on a strenuous second job, your first port of call should be your very own skillset. If you have a natural talent that could help others, you have an instant “in” to easy money. Whether you’re a gifted guitarist, mathematical genius or speak a second language, almost any talent can be turned into cash. Offering one-to-one coaching is a flexible way to make a solid hourly rate, and enables you to take on as much or as little work as you wish. Find local clients by placing adverts in the library, schools and community bulletin boards and share your talent in exchange for a fee.
In focusing on your wealth management goals, investment income is obviously critical but you might fund your goals from wider sources of income.  A typical long-term portfolio might produce about half its return as income and the other half as capital growth, though in times of duress the capital growth component wanes.  In this low-interest rate climate, some sources of income have become quite expensive and may prove disappointing against your spending needs.  But by tax efficiently and sustainably drawing income from wider sources, you might meet your goals while more prudently balancing risk against reward.