Billy, you are right, I forgot all the Federal lands that they own. The banks own a lot of mortgages, home, buildings, etc., but the Feds own half of all the land west of the Mississippi and most of Alaska. National forests, national grasslands, military bases, deserts, etc. Reagan had the Grace commission do a study and the government could sell off a lot of the land and buildings they own and pay off the national debt. For instance they own a big section of Wakiki beach in Hawaii. It was bought during WWII as a place for officers to relax when they came in to Pearl for resupply and shore leave. Now it is worth millions and they really don't need it. I have been to Key West. They have a small unused naval base down there. Only cruise ships dock there and have to be trammed through the base (which is vacant) to the center of town for the tourists. They could sell this base to a cruise company or to hotel-motel developers for a pretty good sum. It is no longer needed as it isn't big enough for but one or two ships at a time. With the super carriers, they need large deepwater ports. If the feds eventually become bankrupt, you better believe lands near developed areas would be sold, because you can't tax Americans enough to pay what they owe.
They could also consolidate military bases with joint training. In Alabama, Ft. Rucker is about 60-75 miles north east of Eglin Air force base. Eglin is 10 times larger. Ft. Rucker is used for helicopter training for the Army. Eglin also has helicopter training for the Air Force. They could close Ft. Rucker and move the training to Eglin and train with the Air Force. Problem is congresscritters and senators from various states don't want any bases closed in their states. The military should make that decision as to what is most cost effective under the secretary of Defence no matter what branch of service.
I vote they should sell a lot of bases and use the money to buy land along the Mexican border for bases. Would cut down on illegal immigration real quick with artillery training, bombing training etc, live fire training for tanks and soldiers. Kill two birds with one stone without spending a whole lot of money. They could plant mines for training.