So this works for me but it does involve some work. The quick and easy way to clean a ruck is to take it to the carwash, hang it up on the floor mat part and then blast it with the high pressure hose. It helps get the majority of sand out of the ruck and pockets. That gets the dirt out. If your ruck stinks then I found that this works every time. Also works great for hats or smelly clothing.
1) Baking soda
3) 5 gallon bucket
5) Hot water
6) Color safe bleach (optional)
First thing you do is open the beer and chug it. Next, combine ingredients into bucket. Have another beer. Throw ruck in there. Have all the beers. Wait 12 hours. Empty out bucket.
Rinse and repeat.
That is the Eric Wang Method.