One more consonant remains, ‘x.’
Every rational spelling of English acknowledges that ‘x’ is redundant, and should be spelled ‘ks.’ Let’s ignore the fact that according to the rules we have so far, it would be ‘cs,’ and instead embrace it. Here’s the rule: wherever the sounds ‘k,’ ‘s’ occur in order, they are written ‘x.’ Always!
You might think that this would lead to many funny spellings, but it doesn’t kick in that often. We get, for example, ‘sox,’ ‘hax’ and ‘sux,’ and more interesting examples like ‘suxeed,’ ‘blaxmith’ and ‘oxidental,’ which all look amusing rather than ugly. So this is obviously the right decision.