I have tried everything suggested, but my file is still HUGE on import to Design Space.

Sizing is one of the biggest issues with Inkscape. We all go back and forth on the best ways to size things properly in Inkscape so that SVGs upload properly. You will likely continue to encounter issues. Sadly, Inkscape SVGs don't play as well with things like Cricut Design Space as Illustrator SVGs. But as long as you're willing to keep experimenting and trying things until you get it right, it's fine. 

Sometimes when all else fails, open the new-design.svg file in your illustration software, copy and paste your file into this new-design.svg document, and save it as a SVG file. Upload your file to Cricut Design Space.

If you're using Illustrator you may also occasionally have issues, so here's a trick for you: Go to Select > All, then go to Object > Artboards > Fit to Selected Art, then save your SVG and upload again.