Hi Ginger,
I think that 28 ILD would be a little on the firm side for many people so it sounds like you are included in that group as well.
I may have linked some of these already in our previous conversations but the Roanoke list is in post #5 here, the High Point / Greensboro list is in post #2 here, the Charlotte, NC list is in post #2 here, the Wilmington list is in post #5 here, and the Myrtle Beach list is in post #4 here which are the forum lists that would be along the way from Roanoke to Myrtle Beach.
I don’t know which of these carry toppers that you could test (hopefully on a mattress that is similar to yours so that the combination is reasonably close) so you would need to check their websites or talk to them before you go.
Phoenix