Well, you cant fit a one piece into any existing room, which is why they make 2 and 3 piece "remodel" units. These fibreglass units will give good sercvice. A better choice for a rental might be an inexpensive steel tub, and glued up tub surround walls such as those by Maax, American Shower and Bath, or E.L. Mustee.
If you trulty have 67" that will make it much easier to get a new tub in without so much demolition of existing drywall. You can then fur the wall to trim out the new tub.