Hi Ethan - what we have done is to customise the OOTB page, however I created a copy of it before amending it, as point of reference. I cannot recall if best practice is to create a copy and customise that one - I know this was the advice for widgets so I guess it would extend to Pages as well.
We have customised widgets as well and in their case I have used the copies, not the originals.
"Also is there any way I can set the new project status page as default?" - I suppose you refer to how you can be sure the new page is being picked up when checking the Planning Console/Status Report tab. It's been a while since I worked on this, but if I remember correctly you need to ensure it is aligned to Project Portfolio Suite Portal Package, as shown in your screen shot. so if you create a copy, align it with this package and the previous one (OOTB) move to it Global.
Hope this helps a bit 🙂
