1. Keep writing to all your senators and congressional reps.
2. Keep contributing to the AOPA PAC.
3. Keep encouraging all your friends to do the same.
As you note, individual letters to the docket don't carry a whole lot of weight, but the mass of them gets Congressional attention as they know the writers vote. Also, keep in mind that even if the ADIZ does become permanent, we can still help create a workable ADIZ with appropriate changes, including:
1. Incongruent boundaries of the B-space and ADIZ. Pilots have extreme difficulty navigating around the ADIZ where it doesn't match the B-space. The lateral boundaries of the ADIZ and B-space should be aligned, and they should be based on reasonable visually perceptible landmarks.
2. Inclusion of the 4000-foot base B-space extension out over Easton in the ADIZ. This cuts off north/south VFR traffic that is well outside the 30nm arc around the national capital area, creating additional demands for ADIZ squawks on that route.
3. Lack of convenient gaps to transit around the ADIZ VFR, especially around Patuxent and Dahlgren, due to preexisting R-areas. The ADIZ presses up against closed airspace, particularly on the southeast side (R-4005/4006) and south side (Dahlgren R-areas -- R-6611 and R-6613, IIRC, and the Fort Picket MOA and R-area). There's just no way to get through these areas VFR without going through the ADIZ, and that unnecessarily adds to Potomac TRACON's workload. Going around is often impractical and sometimes impossible due to the extra distance required and altitude restrictions of the R-areas.
4. Insufficient controller assets to allow VFR traffic going all the way across to go through rather than under/around the B-space (especially virtual closure of the north/south Dulles East transition). Controllers generally deny VFR entry into the B-space due to workload, and this concentrates VFR traffic in the few spaces available to transit the ADIZ without being in the B-space. That has a negative impact on safety by increasing traffic density in "see and avoid" areas and forcing aircraft to fly head to head at the same altitude, especially at 1200-1400 MSL in the very narrow NW/SE "Fort Meade slot."
5. Insufficient controller assets and frequencies to meet demand for VFR squawks -- 126.75 isn't enough to cover 360 degrees around the ADIZ without lengthy delays while waiting one's turn to make contact, and many transmissions blocked by the multitude of aircraft attempting to call at once. They need at least three controllers handling this on a sectoral basis (say, MTN to PXT, PXT to Casanova, Casanova to FDK, and FDK to MTN) when the weather is VMC, especially on weekends.
I'm not saying we should just accept the ADIZ as a given, but we need to let folks know the problems with it that are making life impossible for everyone from pilots to controllers to the USAF folks in Huntress to the FAA inspectors investigating all the infractions of the rules. If we can fix these issues, the politicians and security folks can still have their ADIZ, but we can operate safely and easily in and around it.