Boost Knock Spell?

[Lucian_Navarro]

Then its confirmed that next mod a lvl 20 wizard or even a sorc can knock many currently unknockble high end doors and all chests.

a caster with 40 of their major stat would have a +15 Int Mod. with the capstone, a +16 Int mod. if they got the abbot trinket (and were not good aligned) and a +4 tome, they'd have a +17.

20 Caster lvl+16 Int Mod+a roll of 20 on a d20 roll=56 (Essentially a total roll of a 56 if you were translating that into a rogue's roll). I think that's enough to knock every chest and knock almost every door if not every door at mod 9's lvl 20 cap.

You could even use an Alchemical Potion for an additional DC.