Just getting started:
How about Randle + Knox + Ellington + Franc
for
Brad Beal and Mahinmi?
Knix consolidate some players into an all-star.
Mahinmi an ending contract.
Think they'd want more, tbh. As you concede, they may not have a need for Randle. Ellington makes more sense on a contender. Ntilikina may or may not be rated by the Wiz.
I think we should target Beal. The most obvious deal is:
Beal/Wall/two or three minimum players for Portis/Mook/Payton/Ellington/Taj/Knox (or if we can get away with it, Trier)
Wall has the worst contract in the league. The Knicks are the team best suited to absorb that terrible contract since acquiring Beal would mean passing on free agency and building around Beal/Randle/DSJ/RJ/Knox or Trier/Meech/Ntilikina/Braz and a lot of picks which can be used to aggregate in trades. And then the Knicks just pay the inevitable luxury tax in a few years, which others teams will want to eschew.
The drawback is with that anchor of a contract it really becomes difficult to improve the team in the medium term. It's hard to see Wall returning to all-star form; more likely he isn't good enough or healthy enough to start 70 games a year ever again.
Would you do such a deal, given it does not involve picks?
A more complicated version of the deal is finding a team that really wants Mook for a playoff run and is willing to trade a pick for him. It's tough to see who that is - maybe Atlanta would trade the Brooklyn first and Chandler Parsons for Mook + Ellington? If so, we flip Parsons and the pick over to Washington so we can keep Knox (or maybe keep the pick ourselves?).
If we're trying to acquire Beal without taking on Wall, I'm afraid the price will get pretty high. They're going to ask for Mitch or RJ. Even if they agree to DSJ (say, DSJ/Portis/Ellington), they're going to want our pick this year and the Dallas pick next year.
If they'd take Knox/Portis/Ellington and our top-5 protected pick this year and our pick next year, I'd happily do it. I' m worried that won't be enough.