@AdamBeGood You don't have apologize or be sorry for anything. Asking questions and seeking for help is what this forum is there for :-)
Under DOSbox, swapping discs around is not clearly indicated as you experienced yourself! Yet it does work flawless. Let me share a quick hint as well that could come in handy.
Some games do support natively multiple CDROM drives. Meaning you can mount the different "isos" images and assign these to different drives letters. As you mentioned Command & Conquer let's use this as an example below. Just add something like that in your [autoexec] section:
imgmount d /home/pi/RetroPie/roms/pc/isos/comcon/CaCCD1.iso -t cdrom
imgmount e /home/pi/RetroPie/roms/pc/isos/comcon/CaCCD2.iso -t cdrom
mount c /home/pi/RetroPie/roms/pc/games
Then no more disc swapping in-game :-) Other games where this is working which I've tested: Under a Killing Moon, Ripper (6 discs!!), Pandora Directive. I haven't tried with the Wing Commander serie so feel free to report back if you have some success!!
Interesting! And I guess that would work with three disks to accommodate Covert Operations also? Great tip!
Edit - that didn't seem to work for me actually with Covert Ops.. but it may be something I am doing wrong here. That is quite likely. Everything works perfectly so I won't push my luck!
@meynti The backup image contains 2 partitions, one for boot and one for the system itself. The 2nd partition is formatted with the Linux ext4 filesystem and cannot be read by Windows. You'll need a Linux system to be able to read it - either try a live linux distro (that you can run from an USB drive on your Windows PC) or find a Linux installed pc to read the image.