I actually think signing Tosun could solve 2 positions. I think because DCL wins so many headers, and does a lot well, but is a poor finisher, he could naturally move out to Lennon's spot. He has good speed though its deceptive, and he has a high work rate so he should be willing to get back defensively. This way he isnt responsible for finishing anymore, and can run the channels like he did earlier in the season. When we hoof the ball up hes pressed up to win headers and flick them on to Tosun, and then defensively just slides back to the right side.
Maybe if you loan Walcott you set up with Tosun up top, Siggurdson in behind, and DCL and Walcott on the wings with DCL coming more centrally and Walcott playing as a more traditional winger.