Hmmm, I'm not sure you can get slowed enough from 350 kts at 12 nm. If you can't get the flaps down to a normal speed what's your expected runway requirements???? It will be very tight.
I've done 340kts (?) to 13nm and the answer was to CLIMB! The plane slows down faster going uphill which allows you to get the drag out sooner. Full speed brakes, gear as fast as allowed, and flaps at the maximum speeds. You'll end up above GS and have an aimpoint short of the runway, at idle power, to regain a normal approach path, and might have speedbrakes deployed below 1000'. You'll be at idle until very short final. So you end up doing a vertical S around the GS, below, above, then an S curve('banana' approach) to re-intercept just prior to the 100'.
Here's some basic stuff to consider -
1. watch Top Gun. Understand the concept of 'do that pilot sh*t Maverick'.
2. do you know your a/c's runway requirements at MTOW or MLW?
3. do you understand how #2 is computed? example given below
4. all jets need approx. 70nm/9 minutes from max certified altitude to stopping on a runway. Typical cruise is slightly lower so 65nm/8 minutes might work. It requires emergency descent and then 320/15nm/2000', or a slightly faster/closer, but still at 2000', rapid configuration while climbing to slightly above GS, and then an unstablized approach. This is what #1 was about.
5. a jet's fastest TAS is in the mid 20's typically. Basically where maximum mach/airspeed crossover is. Add in winds and the decision to climb, or descend, to make the fastest GS might be a factor.
Runway requirement of 10,000' (eg heavy jet at takeoff weight returning to land). The actual distance would be 6000' x 1.67 = 10,020'. Or the actual runway distance used, including a 1000' air distance, will be 60%(.6) of the required distance. Add another pad (1000'?) and you have distance you can use in a dire emergency. That's where knowing #2 helps - you can immediately figure out how short a runway you can accept in serious event.
So what's the math saying? You can land in shorter runways than the 'required' distance in an emergency. Just realize it's a maximum performance effort and a bounce adds air distance and delays the de-acceleration effort.
In training we typically land a 757/767/777, slightly lighter than max landing weight, on a 2887' runway (short runway at KSNA). If you try and land it anything close to normal you go off the far end. It requires flaring short of the runway, idle short of the runway, and touching down as the threshold passes below you.
It's a good training event. Enjoy.