You will have been taught not to use white tips with gel, that is what we teach at CND and this remains the recommendation.
There are many professionals who get a good result using the method geeg explains above. Give it a go, if you experience any problems you can always come back to the method that was recommended by the manufacturer.
I think it is a matter of knowing your products and chemistry. The official CND line is really for safety. If people do not know their chemistry, they could potentially have under-curing if they piled product on over opaque tips.
However if you realise that you need to use nice thin layers to build your clear gels over opaque tips then I have it on authority from speaking to the chemists at CND that you can use clear gels over opaque tips. Without under curing.
CND are quite rightly over cautious because if they were not, then many technicians would abuse the system and get into trouble. Be smart and know your stuff and use the products with knowledge and common sense.