VirtualBox raw drive access using CLI shows only 32-bit guests

[ForeverFree]

Hello, I'm VERY new to Linux but not at all to PC's, only moderately so to VirtualBox; so let me begin by saying that while I'm a partial newb, I'm far from uncomfortable with advanced commands but my primary experience is from the windows environment - if there's anything I've missed providing please let me know or ask (sometimes I may ask a newb question of how) and I will do so (my best) hastily. I have literal decades of experience in the windows environment but I'm slowly eating the elephant and working towards moving my household to Linux and would love virtualbox to be a major component of that.

Question: How do I attach this raw disk image to a 64-bit VM using either of the 2 paths I've been trying, below?

My purpose:
I'm attempting to setup a VM with raw disk access to a secondary sata drive I reserve specifically for work. For various reasons, I need this VM to be 64 bit.

Problem: (2-fold)
Using the various info I've found online, I've been able to create the raw-disk .vmdk, but I have these 2 problems (hit these stops):

A) When I try to add it to my Virtualbox VM (ubuntu 64-bit), in the GUI, of course I get an auth error. So to bypass that I've been primarily chasing a solution on problem path B below, but if there's a way to bypass the auth error for the raw disk image for this path that I haven't found yet, I'm open to it.
1. Using the VB GUI I definitely have the option to create 64-bit guests.

B) After successfully creating the .vmdk as raw and adding my user temporarily to the disk group, I go to start VB from CLI as sudo, and when it starts it only runs in 32-bit mode; I can not see my 64-bit guest VM, and when I try to recreate it I only have 32-bit guest options, so I cannot add my .vmdk to the 64 bit VM previously created by GUI.
1. I have logged out as well as done a restart in between attempts, without success.
2. I have done a locate for VB binaries and do not see any that differentiate between 32 & 64 bit executables.
3. Looking through VB's docs, and searching on the web, I've not been able to verify if this is a restriction on VB's side or LM's because I'm starting it by the terminal instead of the GUI.

My setup (from hardinfo):
Processor Intel(R) Core(TM)2 Duo CPU E8500 @ 3.16GHz (Dell OptiPlex 780)
Memory 15285MB (3676MB used)
Operating System Linux Mint 19.1 Tessa (HOST!)
Kernel Linux 4.15.0-47-generic (x86_64)
DESKTOP_SESSION xfce
VirtualBox Graphical User Interface Version 5.2.18_Ubuntu r123745

I hope someone can offer advice or even a place to look. I've been pouring over various forums and unfortunately most of the people having a similar problem are Windows users, very little on Linux forums.
Thank you in advance.