While I can’t help you with the database part, I can tell you that it sounds like our situations are similar for DIM. I have an SSD for my OS drive. The actual software doesn’t take up that much space. I can’t remember, but I think it’s something like 22 MB, not bad at all, so it didn’t matter that I put it on the SSD. I then directed the zip downloads to go to my backup drive. I believe that’s under the settings gear icon in the top left corner. Then I directed DIM to write over my current DAZ3D directory on my secondary drive, not my SSD. It was pretty easy.
I had to choose the following pathway for my secondary drive: E:/Documents/DAZ3D/Sudio/My Library. Originally I chose E:/Documents/DAZ3D and it put all of the main files there, instead of merging with the files already in My Library. So far I haven’t had a problem with it, but most of my products were up to date. Of course, I made sure to back up my content database before I did this, but it’s working just fine. (I back the content database up regularly by going to the C:\ProgramData\DAZ 3D\Content Management Service\databases and copying those files into a backup location whenever I don’t want to lose what I’ve just categorized. Because it does get corrupted every now and then. There are other ways to back up user data through the program, but I prefer this way)
I didn’t want to uninstall my 3rd party freebies, purchases, etc. That would have been a nightmare. So that’s why I reinstalled over my original location. But so far, it’s working out quite well.
And the upsides are big. It downloads, installs, and uninstalls on its own. That’s so much better than before. It’s saved me tons of time.