As the solo 401k Admin, can Fidelity's account be sufficient?

[Zehua Zhou]

I set up the solo 401k and I am the admin and trustee. I opened Fidelity's non-prototype retirement account and funded it. If I directly hold rental properties under the 401k, and only use this account for operating activities, I need to be able to send out wires for property earnest money and down payments, and also provide the account number to my property manager if I need to make a contribution or if they give me monthly rental distributions. I would prefer not to write a check though I know this account allows check writing.

Has anyone used Fidelity's account for the solo 401k and find it sufficient? I would prefer not to open a conventional bank account if I can keep things simple.