You ain't the first person to say that.
As far as printing the covers, most cover artists buy 13x19 paper in their sheen of choice then cut them down to 8.5x13 sheets.
To print the covers, I just use Windows Paint. Ready?
1) Fire up the cover in Paint.
2) File>Page Setup - Legal size paper, Landscape, Horiz & Vert centering checked, set all printer margins to 0; Paint will re-adjust them to your printer's minimum defaults.
3) File>Print in your printers Best/Highest quality mode.
4) Go back to step 1 with the next cover.
As long as you don't shut down Paint in between covers, it will retain the margin/orientation settings.