I have found that doing the BLS skills in a most rapid fashion, getting into a transport ambulance and starting out for the closest appropriate hospital without delay while doing the required ALS skills enroute to the hospital has always served the patients well.
Paramedics usually don't like to admit it but the BLS will save the day in this instance. Not saying their is no role for the ALS especially when the number of victims exceeds the available transport resources and you are in a designated treatment area where some advanced skills might be needed and performed so I would always ask for a Paramedic unit(s) to be assigned.
When you actually look at what the ALS can do above what the EMT's or CFRD Firefighters (NYC specific) have likely already done for the patient and the feasibility and safety of doing those skills in a moving ambulance (not easy) you will likely rethink your approach and the need for ALS. IV fluids don't carry oxygen only blood does that so don't get all wrapped up in needing to start a one. In my experience that only slows things down. I'll give you the chest decompression because that will turn things around quickly but even that requires a good size needle and some landmarking to be successful so it might not be as easy as your thinking. Get in, get out and get moving. Focus on the BLS.
My experience is NYC specific, we have many ambulances and our hospital system is robust so out transport times are not likely as long as others in different parts of the world. The key take away is that one approach does not fit all situations. Know your response district. If you go mutual aid then get to know that district also. Develop a plan that works for your system. What works in NYC might be great for us but not for you. Lastly, Drill,Drill,Drill. Include ALL of your assets - Police,Fire,EMS,Hospitals, have a traffic plan and include any other agency in your town/city that is going to have a positive impact on your ability to give the greatest number of individuals (that includes us !) the greatest chance getting back to their families in one piece- .
Remember - The police will stop the killing - The rest of us stop the dying. It won't be an easy day but then again nobody ever said it would be.