I see you got no responses, so let's see if this helps.

You seem to be asking to do something that no longer exists (form 2106 is gone and Sched E doesn't apply):

https://www.tlnt.com/dont-let-your-people-be-surprised-when-they-cant-deduct-work-expenses/

You might also like to read the IRS literature, along with such blog posts from the web (always confirm the date so that you know this is post TCJA) as:

https://www.kitces.com/blog/accountable-plan-s-corp-owner-employee-deduct-business-expenses/

For Mileage, your client still has time to submit and substantiate to the corporation, and that is reimbursed at Allowance rates:

https://www.motus.com/mileage-deduction-tax-day-2020/