[elmomle]

Or more simply (and with fewer alterations to how swimming competitions work today), just have a couple of unused lanes on the outside of the pool.

[trillic]

This already happens in SCM and SCY competitions as many short course pools are just the short side of a long course pool.

[necovek]

To avoid turbulence, you'd have to skip lanes (or make them very wide) and allow enough space between the pool side walls and outermost lanes, right?

[rpearl]

this is what is done in most major competitions already