[Closed] 26" 48h tandem rims - wider options?

Experimenting with making our Dawes discovery twin tandem suitable for a bit of light off road action but think I need to fit a wider rear rim, past experience tells me I want at least 21mm inner for a 2.3" tyre but that's just solo, should I go wider for maximum squish? But also needs to be okay for 1.75" tyre when we go touring again & ideally suited to rim brakes for parking brake 😎 - any ideas what I should be looking at?

*rear wheel needs rebuilding anyway after breaking 4 spokes in recent weeks, so new rim and spokes seems the sensible option.