If it helps, this is what I used on a 1m wide gantry, and is commonly recommend here because of the spacing matching up well with BK12s.

https://www.aluminium-profile.co.uk/...file-kjn990300

Some of the bits I think are important are the heavy duty nature and the associated increases in moment of inertia which can be used to calculate deformation under load.

I've combined two of these into an L, so my gantry occupies 135 x 90.