Last year I edited a whole feature film off of a 4TB SSD card using only proxies. The original footage was kept on over 30TB of external storage. I only touched the original footage at the end, when we were preparing for color. So yes, you can swap out the proxies for the original, it happens all the time. In fact, if you don’t have the originals in place, you will get an error message when you try to export telling you that the sequence contains offline material (which includes proxies). Just do a test first, keep your full-res material on one hard drive, and your proxies and project on another, than turn off the hard drive with the full-res. You will figure it out, and then you can create the same scenario putting the full-res on a server online someplace.