Agreed it's not easy to rent for longer periods, but it's definitely possible without committing to 5 hrs per day, which is impracticable for a private pilot. Much depends on forming a relationship to convey your experience and reliability, perhaps on the phone but better face to face. 3 hrs is a more reasonable objective and probably closer to what they'll average on training, especially at quiet times of year. Your booking is a valuable slice of revenue, after all. It's important to choose an operator who has several aircraft of the same type, so they are not losing some unique training resource. I'll never forget the expression on the CFI's face in Ardmore, New Zealand when I walked through the door on time on the appointed day for my check ride. Evidently most Brits are dreamers who don't show up!