Having only been following the team for the last year after being a Chargers fan for 25 years I would do the following...
1. Cut: Dawson, Mauro, A Peterson and all other dead wood
2. Restructure, but if not cut: Bucannon, Veldheer, Iupati
3. Restructure: Mathieu (attempt to at least)
4. Trade: Gresham for late pick - 6th/7th (if he doesn't go then we are stuck with him)
5. Re-Sign: Jaron Brown, Niklas, K Williams, Gabbert, Bynes, Martin, Boone, T Williams, X Williams, Pierre.
6. FA signings (23m in cap) - Norwell OG, Lotulelei DT, Moncrief WR, Attaochu DE/LB, Matt Slauson OG/OC, Kyle Fuller CB
7. Draft (assumptions are that Cousins went to a top 10 pick team).
1: Mayfield/Darnold QB (giving up 1st, 3rd, 5th and next years 2nd - according to draft value chart we can move up to 5th with those)
2: Mark Andrews TE
Draft on out with BPA in WR/CB/LB
Start our rookie QB straight away and have another mediocre season, the following year draft big in OL, WR and make a run