Yes, it is possible! While we generally say our spray tans will last 5-7 days it is possible to maintain a decent colour for up to 10 days with a few after-care tips. I tested them myself with my last spray tan and was pleasantly surprised at how long it lasted.
Firstly – make sure you are not using a soap or shower gel with any natural exfoliant in it (e.g. anything that has a lactic or glycolic acid). You want something gentle that cleanses without stripping (I like the Coconut Pure Fiji Body Wash or a Dove Moisturising shower gel).
Secondly – moisturise, moisturise, moisturise! This is especially important around the shin and knee area to ensure that when the tan fades, it does so evenly without looking patchy against dry skin. Doing this daily (even better, twice a day) will be the biggest single thing you can do to extend the life of your tan. Using a moisturiser with a hint of DHA in it is also a great idea. The Bronzer gradual tan is one of the best. The best moisturisers are those that feel thick and creamy but absorb into the skin easily, without sitting on the surface like a film.