... its a must do when dealing with commercial clients.
No it's not.
And by the time a commercial company finds out that you just use a private account, it's too late, you've cleaned their windows and invoiced them. The 'poshest' account I've had was the Hilton Hotel Newport, and they never batted an eye-lid. Neither do any of my current commercial accounts; and not only that, the guy/gal who contracted you will usually be different from the person who writes out the cheque, so from the point of view of 'appearing professional', a business account is wasted there too.
I've never had a problem using a personal account.