The trundle will definitely not fit an 8” mattress, as we have carpet.  However, our carpet and pad are not two inches thick.  I am pleased that we waited for its arrival before ordering that mattress.  I wish we would have done the same for the top mattress, as a 10” makes it difficult to make the bed as it has to be stuffed down and behind the back wood piece.  
It is solid wood and looks beautiful.  All pieces are numbered making it easy to put together.  It took me two hours to complete by myself.