For something with 8000 sheets I would sew each region for a specific feature together. Then possibly break it into logically areas and maybe use them to trim each solid for each area. Ultimately uniting the solids together. Hopefully this would give you a structure solid that is somewhat editable if you needed.
If there is no need to changes it later why would you not just sew it region by region as above and just create a single solid for what ever you need it for. You could always remove a group/sheets and replace them individually if required.
It depends alot on what you are trying to achieve IE is this going to require regular changes or not, hopefully not?
Do you just require the solid intially then you can modify it as you like, can you give more details about the component and what are your requirements as to what you need to do with it after you have developed the solid.
This would be most helpful in determining what would be the best course of action to take as with something with this amount of geometry you need to establish you requirements clearly before you start.
Otherwise you could waste a lot of time. Any further info you could give would really help.
What's the issue in regards to the number of sheets & using Sew? You select the first (Target) sheet then window the rest to be sewn together. The processing time may be a while, but as far as how long it takes to specify what to sew, that doesn't take much time at all.
Are you familiar with the Quilt option? You can sew a region of sheets together, specify section & cross strings (usually the perimeter of the sewn body works well) followed by projection vector & the sheets to be approximated & UG will output a single sheet. Simplify may also work after sewing.
