There are lots of 30mm tub rims to choose from. I think they should be a bit stiffer than the shallow box section rims and only heavier by a few grams.
Carbon clinchers are likely to delaminate if you ride interesting roads.
I can only see 38mm or 24mm for most Chinese carbon places...
Plus, I had considered tubs but wonder whether they may be a bit of a risk (even here with the nice roads, the mountain roads are a full of stones etc that may cause punctures).
There are lots of 30mm tub rims to choose from. I think they should be a bit stiffer than the shallow box section rims and only heavier by a few grams.
Carbon clinchers are likely to delaminate if you ride interesting roads.