It really takes practice to be able to deal with a large number of sims effectively and efficiently. Im having my Adam and Evelina have 4 kids and the next generation will probably have 5. Im not counting on my save lasting for more than 10 generations, so Im aiming to completely the challenge in 10 generations. With this comes the challenge of managing a full household of sims, as well as unlocking and building community lots.
To be honest, it really is all about practice and experience. Even if you only unlock and build one community lot this generation, its better than nothing, right? Just allow your sims to have only 2 or 3 kids in the next generation to give you a bit of a break.
One tip I can give you is absolutely abuse the pause button and use the Relativity mod (if you use mods). The MultiTab is also an absolute god-send.