Spread axles over 10’ 1" are classed as two single axles, for both scales and bridge, therefore the 40’ or 41’ or whatever rules do not apply to them.
The same applies to fixed bogie 48’ trailers, for obvious reasons.
California has it’s stupid and unconstitutional law about side skirts and low rolling resistance tyres, but this only applies to 53’ trailers, get one built at 52’ 11" and it doesn’t need to comply