This being said... Will I'd really like to hear your thoughts on how to play vs Fox and how to play vs TL. Playing it IRL vs watching your matches with NAKAT and such is a lot different. I feel I did really well in both these match-ups but any advice is good advice.
I´m not Will, but.... I main Fox and DK , so I feel like I know the MU better than anyone I´ve ever met...
Mostly.... don´t run into him, facing him. If you do this you have no reliable answer to his fair.
Approach mainly with your back facing him. If he commits to a dash or run, drift away in the air and bair or dj bair. retreating bair is pretty safe against him. Minimize sh doube bair (only retreating), good foxes will punish between the bairs.
If you hit the fox with a few bairs (so he´s afraif of your foot :D) try airdoge to grab mixups.
If he tries to approach above you walk/run away and bair him, when he comes down. Fox aerial mobility is rather bad.
Never try to shieldgrab a bair, it´s safe on shield (except when powershielded and spaced poorly).
If you get hit by fair try to DI down and into him, because fox fair has a rising motion. If you get hit by dair simply press to the left/right/away and try to powershield the utilt/usmash (fox can grab though).
ftilt is not safe on his shield. dtilt should be safe. Try to get fox offstage and keep him there with bair/invincicopter.
So its basically approach with your back/bair really slowly. charge your punch and get, keep him offstage.