Recall custom hold shutter type

I have a recall custom hold setup for ISO320 and ISO100 on my A7RIV. It would be nice to be able to switch from mechanical shutter 1/3200 rapid movement to the ISO320 and ISO100 custom holds with lower shutter speeds, but the shutter type doesn't change.

I can rotate the mode dial or push another button to change shutter type, but that's a bit difficult to do quickly in a calm moment and revert waiting for fast motion. The mechanical shutter shake noticeably blurs images with the lower shutter speeds and the electronic shutter produces more frequently sharper images with the 200-600mm lens. I usually take a burst of a still subject to try to get one low noise and sharp still subject.

Does any camera let you change the shutter type with the quick recall custom hold?

Since you're mentioning shutter shock - at least it sounds like you are - why aren't you using EFCS?

e-Front Curtain Shutter is turned on. The mechanical shutter with that setting still produces more motion blurred images at say 1/100s than the fully electronic shutter in a low-shutter speed burst at 600+mm. The burst is handy to get low noise on a static subject, but the vibration mitigate isn't perfect, so it's probably 40-50% sharp with electronic shutter and 10-20% with half mechanical shutter.

Wouldn't the burst mitigate the benefit of e-front curtain shutter since it was preceded by another shot with the closing curtain shutter causing vibration?