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 and was pleasantly surprised at how long my tan 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 Pure Fiji shower gel or any moisturizing body washes).
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 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 best moisturisers are Pure Fiji oils. I love these because they can be applied over your wet body at the end of your shower, hop out and pat dry – your done!