Custom Exposure Bracketing

[LuxImCo]

Hi folks!  New to the A7III (receiving it tomorrow) and new to the forum.  I have a specific scenario that would help me and my photographers tremendously and wanted to see if there is a way to make this happen on the A7III.

We do a lot of real estate photography.  We take thousands of images daily in coastal location all over the southeast.  We always bracket 9 JPGS and deal with them in Photomatix before moving the "merged" images into Photoshop for batch action processing.  For the 9 brackets we use every time is (-5, -4, -3, -2, -1, 0, +1, +2, +3).  Those setting work perfectly for us on 90% of the properties we shoot.  That allows us to get great interiors while seeing the ocean out the windows at the same time.  However, 1 in 10 homes have a beach view with a dark interior.  For those we need to get brackets at (-8, -7 and -6) to add to the original set of 9 brackets above.  And by doing that we are in great shape.  We then have a clear window view and a great interior.  The way we have done it for years on Canon cameras is to take the first set of 9 brackets.  Then use the "wheel" to move the entire set of 9 brackets all the way down so the darkest of the 9 starts with (-8 and goes up to 0 for the brightest exposure).  That works.  However, 50% of the time while the photographer is rotating the wheel the camera gets shifted slightly.  Creating an alignment issue.

All that said, does anyone know of a way to have the camera bracket more that 9 exposures?  Even if we took the first 9 exposures (-5, -4, -3, -2, -1, 0, +1, +2, +3) and had to press a button before we take 2nd set of 9 (-8, -7, -6, -5, -4, -3, -2, -1, 0) that would be fine.  Pressing a button between sets should cause less camera movement that scrolling a wheel (I would think).

Lastly, I understand all about RAW and how we could achieve what we want shooting that way.  I get all of that.  However, our business model and work flow requires that we do what is stated above using JPGS.

Can anyone help with ideas on this?  I hope it makes sense!

Thanks!