Hi,
How bizzare your story is exactly the same as mine. Im after a 3080 as well (not Ti, think thats a bit too much!)
i have a ryzen 5 with vega graphics card. Ive moved up (or over) from Element 3d and After Effects. Really struggling on big scenes.

The beauty of growing up with Andrew Kramer and E3D was the fact NO ONE had a sh*t hot computer back then. So every1 was posting vids on 'hacks' and 'workarounds'

Seen a great one on Adolf Navarro Antareus YouTube Channel. He renders out background characters in Alpha channel format. They can still cast shadows etc. He got a hug fight scene. The 2 main characters are iclone models doing their stuff and ALL the other characters in background are rendered out videos. The scene looks amazing. 
Another is LODs. Make sure you layer any scene. Making sure characters or objects in the background have a low poly and low texture count
Try to render items out. Work on storyboard and once the scene is set. Think of things in your scene you can render out. I bought the popvideo3 just for ALPHA CHANNEL renders. 
My advice is try and watch as many of the reallusion youtube tips. Every now and then they'll show u a setting to check to ease the load. When u render, make sure you un check them all 
Set everything to low quality. The mesh, the texture. Tick EVERY box that is of low quality.

If you got after effects there a load of great hacks especially if u can render out passes.

If i had a dollar for everytime i seen a PRO doing this method id be rich. So dont be put off .
If you want me to dig out any tutorials i can drop sum links in here.
Cheers