Baseal13

There isn't really an elegant way to strength the frame of the screen unless you want to take it apart, and manufacture a custom part/frame that is stiffer while trying to keep the form factor. 
 
Only other way really to stiffen would be to adhere a some thick aluminum plate to the whole top case to stiffen it but that is less than appealing. 

Doesn't need to be a zephrus but the R9 4900HS is the CPU I would go for within your budget. 
 
Models with this CPU are just releasing you may need to wait a bit but I would say it is worth it. 

That's a relatively small a contribution to make, compared to buying 1
 
pandemic

With a crossover ethernet cable, yes.
I agree, can be kind of painful at times, but gaming laptops just don't have them anymore.
 
You can also purchase an external disk reader. 

All good. 
Here is what I think you're asking for. Almost the exact same specs 17 inch screen:
https://www.newegg.com/matte-black-with-gold-diamond-cut-msi-gs-series-gs75-stealth-10sgs-027-gaming-entertainment/p/N82E16834155385?Item=N82E16834155385&quicklink=true
 
300 Hz monitor. Only 1080p, but it's still pretty balls to the wall

With that budget, the best laptop I know of is the Acer Predator Helios 700  with an RTX 2080 and a Intel Core i7 9750H:
 
https://www.amazon.com/Acer-Predator-Helios-PH717-71-75RX-Notebook/dp/B0869LYQ35/ref=sr_1_5?dchild=1&keywords=Acer+Predator+Helios+700+2080&qid=1586725368&s=pc&sr=1-5

You are correct. 
 
Not only did you not tell us that you wanted an i9, you also didn't just do a quick search on newegg. 
 
Here is the link I meant to post:
https://www.newegg.com/core-black-msi-gs-series-gs66-stealth-10sgs-031-gaming-entertainment/p/N82E16834155391?&quicklink=true
This one has the 10980HK. It goes for $3000

Oops, forgot to post the link.
https://www.notebookcheck.net/HP-Omen-17-Laptop-Review-High-end-gaming-with-some-small-limitations.432964.0.html
 
My other options I meant other laptops of the same class which apparently perform better than the HP.

Yes that should be pretty fine for now.
 
No a GPU enclosure won't help when you already have a 2080 built-in.
 
 

Thing is, depending on what games you want to play you'll already be limited with that machine on an Index, let alone with an even higher end headset later.

This will provide a lot more info:
 
And for external solutions:
 

His question was about using one with your current laptop instead. But we don't know what you have so it might not be an option.
 
I would not go with a laptop for that purpose.