I had the same problem with my D35 when I first got it , only my problem was caused by a metal thumb pick . I made a small scratchplate by cutting two Gibson three sided flatpicks to fit to make a sort of diamond shaped plate . It didnt affect the tone and is still there now after thirtyfour years . When I bought my 'spare' guitar (Top of the range Tanglewood) my technique had improved a bit
so i havent marked that one at all !!