The offensive line can and should be better. But I think the "fix" is a 2-year proposition. They are stuck under Whitehair's contract. Daniels is on the last year of his rookie deal. And I'm guessing Leno will be back.
So, think they add a veteran interior lineman. With Daniels able to play LG and C, and Whitehair C and RG, you don't have to have a guy handpicked for the right side. You can even sign an experienced center to solidify the leadership on the line. I think they spend anywhere from 2.5- 6Mil cap hit on the starter. I'd also bring in a vet minimum backup like Kush, Witzmann and Larsen have been in the past. Then, I'd draft a guy by the 5th at the latest.
At tackle, with the assumption Leno stays, in a deep tackle draft, I'd definitely use one of the first 2 picks on RT. And bring in a slightly more than vet minimum swing tackle (think more Cornelius Lucas type than Jason Spriggs type). Has to be good enough to make it worth benching Leno early in the season if he can't get it together.
Leno- Daniels/Whitehair/FA- rookie OT as the starters;
Bench = vet minimum interior, rookie OG, swing OT, last spot between Hambright, Bars, Mustipher, Simmons, whoever.
During the 2021 season, determine if Daniels is worth re-signing. Probably still can't move on from Whitehair until after 2022. But if Daniels is re-signed, draft another OT early in 2022. If not, draft interior OL early and spend money on a FA tackle. Hopefully, your early pick from this coming draft can be moved over to LT in his 2nd year and you only have to spend for a RT as the Bears still won't be flush with cash to throw around.