You would still need some epic luck.
I think right now if you really wanted to break a block you would need over 1 Exahash to have a really good shot.
Just don't forget every hash has an equal chance of being a block so even with a large rental it's no guarantee you would find a one..
1 Exahash
Chance per block: 1 in 88
Chance per day: 1 in 1
Time estimate: 15 hours
Just don't throw money at a rental that you may need in future your basically gambling with any funds you throw at solo mining.