So, there are some dynamics in motion with your approach. The idea of a 4000 gal off road vehicle is going to have some limitations, just like other apparatus. Many bridges in the rural parts of CA are rated at 26,000 lbs. less, so weight becomes a significant factor to consider. The State (CalFire) who also performs fleet management and specifications for some county agencies such as Napa County Fire, is moving away from the larger capacity water tenders primarily due to the lack of manueverability and the weight. There is a high degree of trade offs involved in wildland equipment and placement. The larger the piece of equipment is, the less manueverable it is so it takes longer to insert it into an effective and safe point. Also, once a piece of equipment is off a maintained road, the greater degree of risk of slipping off the road, either from a tight turn or poor road bed compaction and natural erosion. These are key elements of consideration for the command staff as well as the operator when inserting any piece of equipment into a hot line area. Effective safety zones and retreat are also elements in those decisions. As for tracked vehicles such as skid-gens or similar, they are effective to a degree but they are slow moving relatively speaking and require a transport vehicle to bring them to the incident. In a fast moving fire such as the Camp Fire, it would be unlikely that they could keep pace to be effective. Placement ahead of the main fire could provide some assistance but again in the case of the Camp Fire, ingress into the areas where they could be effective becomes an issue.
As you poke around this form, you will see a fairly lengthy discussion about the new Cal OES Type 6 engines that are being ordered.
There is absolutely no single magic silver bullet for any of this but the biggest and probably the most difficult element to control is that the people who live in the WUI area, have to become more invested in their own defensible space. Those who are diligent about their clearance stand a far better chance of retaining their home and possessions. Preparation also includes a primary and secondary exit plan if there is a situation that requires rapid exit. If available a third exit strategy is a good to have as well.
Unfortunately, it has been my experience that there is a tremendous lack of common sense in people who have left the urban living environment to a more rural living situation. Those of us that grew up in rural setting are raised to understand that wildland fires are a fact of life and that we remain prepared for it at all times but the urban transplants have a much more difficult time relating to that fact.
My advice is to be prepared, both physically and mentally, then as calmly as you can exit the area quickly and not wait to be told to do so. All first responders are committed to the safety of the public but the facts are, these scenarios such as the Camp Fire, resources are often thin, particularly in the early stages of the incident.
None of my commentary is meant to be disparaging or critical of your ideas but the reality is that there is no perfect answer or perfect piece of equipment that will solve each and every situation.
