This is where coaching comes into play. You can set defensive alignments to not allow offenses to double/triple team Donald.
For example,
LB LB
E AD NT E OLB
T G C G T TE
Apologies for the graphics--but take this alignment. If any combination of players double Donald they are potentially allowing 2 free rushers including the backers. I am ignoring rb blocks in pass protection as if they need a rb on Donald I'm calling that a win.
This ignores any games/stunts as well. Wes iso'd Donald often by putting him on the EDGE. Which is very good imo. The number of combinations for alignment is endless. Donald can and should definitely be schemed to enjoy the benefit of one v one matchups on pass downs at least. Running downs it is harder due to gap control but the running game doesnt matter. Haha.
The Patriots have had awesome success with quality dbs rushing five journeyman-ish players. You use talent to cover and scheme to pass rush. That's today's NFL.