Why not just have the restriction of having to be a captain before purchasing an engine tanker? They're so infrequently used in missions that it would provide a chance for the possible missions to be expanded for rural style areas.
I am a little confused about your post here. You say you want it to be expanded to rural style areas and get an engine "tender" as a unit. How many tenders do you see out there that also have COMPLETE pumping capability as an engine as well. In my area at least I only know of one and every fire department in my area has 1, some have 2, and some have 3 tenders, but a tender engine combo is rare. if that makes sense? Rural areas is where a tender is more likely used then a big city. Big cities don't have much of a use for them as they have a water supply system often already in place.
We have rescue ambulance on a list of potential future updates. We can revisit the idea of wild land firefighting, although bulldozers and fire helicopters are primarily west coast assets in the United States
I do think that bulldozers are used all over the US By the USFS. Not just in California. Thought I'd point it out so it could find at least maybe some functionality for big wildland fires, have a USFS fire station with a delayed response time. All my area is covered by a couple USFS fire fighters so it takes them time to get where they are called to with their trailer and equipment.