[Closed] CX wheel rim size?

Building up CX bike and currently have a mavic kystrium elite back wheel(front one AWOL).

Mostly using bike for commuting but also aim to do the CX session in winter and go out with mates ect.

So with this in mind, do i;

1:Keep mavic elite back wheel( plenty of life left) and stick a 30mm tyre on it, as i hear even though mavic advises not to, it still possible? then buy another mavic elite front wheel/ lower speced one.

2: Sell mavic elite wheel (maybe £100-120) and buy a new wheelset and if so which one be best, with commuting in mind as well.?

thanks