Picard, let me make you and others aware of my all time favorite trousers. Take a look at the trousers on eBay item number 6 5 4 5 0 2 9 5 0 8 (I'm not posting any more long URL's). These are genuine military surplus and are the best I ever owned. All the pockets have snaps, there are two huge cargo pockets on the legs (with internal straps to tie around your leg for snugness) and the cuffs have drawstrings. They are heavy cotton sateen and have internal buttons for a liner. They are not waterproof but they cut the wind pretty well. They are left over from the Korean War and appear regularly on eBay. Some are priced to high ($25 plus S&H) but you can find a bargain if you watch. If you are an eBay member, enter M1951 Field Trousers in "My Favorite Search" and eBay will automatically notify you anytime a pair come up for sale. They are extremely roomy almost to being baggy but this is good for the field. Also, the fly has a good durable zipper as well as suspender buttons on the outside of the waist. They come in regular and long but I would recommend you don't buy the long unless you are seven foot tall. I am 6-2 and the regulars are PLENTY long.
There is also a pair of take up straps on the sides so the waist size can vary by four or five inches and still fit. Take a look. You won't be disappointed if you buy a pair.