Bad idea:

1: If you up vote someone, this gives him / her Steem because they added value to Steemit. Upvoting good content means you decide that this content will increase the value of the Steemit. How more SP you have the bigger vote you have, but this is a kind of reputation that gives you trust to decide what content is good. Upvoting to rent a house doesn't deliver anything to the value of Steemit, so actually you are draining the platform.

2: The value of an up vote is very volatile, before the hard fork my Upvote was worth 0.02 USD, After 2,28 and till now it went down to 0.38. It will be very hard to maintain a stable value of your up votes, another hard fork or downtrend in price could make the value too low to pay your rent.