Dear friend ,
i think u can not find any opto which has LED input higher than 2volts, always a series resitor is required to drop out the extra voltage and limit the current.
in ur case when u have 5 to 35 volt input using a simple resistor in series is not a right solution , i have attatched a file which shows a simple solution to this problem.its simply a voltage regulator which limits the max. out put voltage to around 5volts then any opto can be drived using apropriate series resitor.
if u find it ok use this circuit , or we can think of something better.
best of luck .
bye
seaspac