[OptiPlex 7070 SFF] question about upgrading storage

Hello.

TL;DR: I would like to set up my OptiPlex 7070 SFF with an M.2 drive, plus two SSD drives attached to the Dell dual-drive caddy, but it is not listed as a supported configuration.

A quick question about upgrading storage on this SFF computer.  In the "Storage combinations" section of the Dell OptiPlex 7070 SFF Setup and Specifications Guide (p.12) there is a listing of some supported combinations of M.2, 2.5-inch and 3.5-inch SSD/HDD storage devices.

Some of these combinations include two 2.5-inch drives (I understand these combinations are achieved using the optional Dell dual-drive caddy), or M.2 + a single 2.5/3.5-inch drive.  It is a bit surprising, however, it is not listed an M.2 drive + two 2.5-inch drives (either SSD or HDD ones).

Is it on purpose?  Is a setup of three drives (one M.2 drive + two 2.5-inch drives attached to the dual drive caddy) unsupported?  Mine arrived with a 3.5-inch caddy, obviously for a single drive, so it arrived with an extra power cable plus a single SATA data cable, intended for the 3.5-inch caddy.

Will adding a second SATA data cable and the power splitter cable provided with the dual-drive caddy, be an unsupported configuration?  There is a free SATA port on the motherboard, and it looks BIOS will be happy with this setup:

[...]

    PCI Information
        Slot1                           = {Empty}
        Slot2                           = {Empty}
        Slot3_M.2                    = Mass Storage
        Slot4_M.2                    = {Empty}

I understand Slot1 and Slot2 are the SATA ports on motherboard, while Slot4 is the M.2 slot destined to host the [optional] wireless adapter.