Can an RPi 4 or 5 power three HDDs?

I hope to use the benefit of experience.

At the moment I'm running OpenMediaVault on a RasPi 3B+ with two 2.5"
portable USB HDDs and a 5V 8 amp PSU.  I've wired across the USB
current detectors and put 9000 microfarads across the 5V supply inside
the case to support the current surges.  This just about holds up,
but when the time comes to copy data across from an old drive to a
third drive prior to replacing the old one, somehow there isn't enough
power. The numbers say it ought to work, but it doesn't.  So I'm
considering upgrading to a later Pi model and PSU.

I have a RasPi 4 that I haven't used yet.  I see there is an official
5.1V 3A PSU.  The extra 100mV should help cover for the inevitable
ohmic losses, and 3 amps means there might be enough current.

Alternatively I could buy a RasPi 5 and a 5V 5A PSU.  Not keen on
only 5V, because 5V in meeans a bit less than 5V out to the HDDs.

I'm looking for the experience of anyone who's actually tried any of
this and found it to work or not to work.  Please only respond if
you've been there.

Thanks,

David