I wish to run tests with more than 1000 users and my machines aren’t powerful enough to handle that kind of traffic.
Really? What do your machines look up? What makes your tests so expensive?
Then, no, there’s nothing more than what you can do with a few scripts + ssh + maybe Graphite.
In Gatling one user does not equal one thread as it would do in JMeter for example. How many requests per second are you aiming to achieve? There is some Linux tuning you can do here:
Does Windows need tuning (I run Windows 8).