Can I have an RV that is my home/office in and claim the standard mileage deduction on, and also claim any repairs done on it under repairs/maintenance of home/office?

Yes, if your home office qualifies as a tax deduction you can use an RV and also claim expenses to maintain the office.  Any mileage that is required to earn your self employment income would be allowed as a deduction.

The information provided below will allow you to determine if you meet the requirements to deduct a home office for your business.  Also included is a TurboTax FAQ for business mileage.

https://ttlc.intuit.com/replies/3302005

https://ttlc.intuit.com/replies/3302360