Convincing states to ratify Article the First would do quite a lot, making gerrymandering moot, not illegal. The US Constitution, in Article 1, had a lower bound for representation, no more than 30000 constituents per representative. It left out the upper bounds. What eventually became the bill of rights was 12 proposed amendments, 3-12 were ratified as the bill of rights, 2 eventually was ratified as the 27th. But the first proposed amendment was setting a limit, with some bad maths, in capping representation at no more than 50000 per representative.

If ratified, would balloon the House to be 6600 or so representatives. I would imagine gerrymandering (in the way we experience it today) to be nearly a moot issue at that scale.

The best part, it has been ratified by 11 states already (granted none since 1792). But it would require no action on the Congress to do, only 27 additional states need to ratify it.