Hi burns_erin,
There is some good information about the pros and cons of different types of mattress protectors and some examples of each of them in post #89 here and the posts it links to.
Unfortunately I don’t keep a list of the pocket depths for each of them or the mattress thicknesses that they would each be suitable for so you would need to check their websites or call them to find out which ones would be suitable and/or would be a tighter fit for an 8" mattress.
Phoenix