The easiest way to shave $$$ is to use a more gas efficient vehicle as it seems the most expensive aspect of traveling to Alaska is the fuel. For example, a huge class A DP gets about 8 mpg. Our tt and truck combo gets 12. Just in fuel alone, we would be spending 33% less.
Some people require hook-ups every where they go. They can spend $30+ per night for the entire 90 nights. Other people boondock a lot or use public campgrounds. They can average $10 per night for the 90 nights, or about 66% less.
Some people prefer to eat out. They can spend $60+ per day on food. Other people only eat at 'home.' They can spend about $15 per day for a savings of about 75%.