You can always make a mass driver system (which is not limited by the rocket equation), but given how insanely hard it is at our own gravity, it would be more i

You can always make a mass driver system (which is not limited by the rocket equation), but given how insanely hard it is at our own gravity, it would be more insanely difficult at a few times great g. So there's definitely a quite low maximum gravity allowing practical space access.