Interestingly, unless it's changed recently, since it's in a 'rural' area (i.e. technically outside the city limits), the Eastern Iowa Airport (CR) was in the area of responsibility of the Ely volunteer fire department, a town of less than 2000 people. The airport does have fire crews, I just always found that odd.
First, 85 % of fire departments are volunteer already, with only 9% of departments as 100% full time. That means that 91% of of fire departments already have volunteers.
I've been involved in the fire service since before I was 16. I'm a fire instructor and have been involved in the fire service in Iowa and Washington state. Very few departments actually have a drinking problem. I've only ever been in one fire station that had alcohol in the fire station and it was supplied by the firefighter to drink after meetings.
If you show up drunk to training, meetings, and especially a fire call and it is taken very seriously as it is a big liability. I don't think it is something that should ever bee present in fire halls, but I would guess that it is less than 10% of fire stations have that issue and it is very uncommon for a intoxicated person to show up at meetings or calls.
I will say that it is a bigger problem in Iowa than it is in Washington.
As for saving homes, I've saved many more homes than were lost over the years. You are thinking a fully engulfed fire, that is not how most structure fires are. Chimney fires, appliance fires, and kitchen fires make up the vast majority of structure calls and with all of them should be relatively minor damage. Even a room engulfed should result in little damage to the rest of the structure if handled properly. This is why training standers needs to be in place.
Most people don't realize when fire departments save these homes as there no way to know after the fact. The only fire results the public ever see's are the ones that burn to the ground.
My first department averaged, 2 accidents a year, 4 structure fires, and 15 wild land fires. Another department I was involved with in Washington (10 miles away from the first) had twice the population and didn't even have 4 structure fires a year, but had ten times the accidents. Every department is different.
Even if they have a hard time responding during the day, what about at night, on the weekends? Remember that if most people are gone during the day that means less chance of something happening.
How can you pull a fire department that could be at someone's door within 10 minutes, and make another department (in a town about the same size) respond 25 minutes all the time?
People from Maxwell won't travel to Cambridge to respond to calls in Maxwell and firefighters in Cambridge would begrudge having to respond to everything. Even if you were to put a department half way between, you are going to cut way back on the number of possible volunteers and reduce response time for both towns as well as destroying the insurance rating for both communities.
Even Collins and Maxwell would be a tough sell.