I’m surprised that you’ve been working with support for that long and they haven’t recommended the standard work around. People have been using this since the fall of 2015.
All you need to do is create a virtual switch and then have that virtual switch coming on turn on whatever routine you want.
The echo won’t even know that the routine exists, it just thinks it’s requesting that a switch be turned on.
But since a routine can run automatically once a switch comes on, that’s all you need.
- create a virtual switch and give it the name that you want to use with echo. I’m going to call mine “nighttime.”
-
create a routine that does whatever you want. It could set up mode. It could set the smart home monitor armed state. It could unlock the lock. It doesn’t matter because echo will not even know that this routine exists.
-
towards the end of the new routine, choose the “happen automatically” options. Here you are going to select the routine should start automatically when your new virtual switch comes on.
If you use a momentary switch, it will turn itself off again as soon as echo turned it on, so it will always be ready for the next time.
If you use a binary switch, you should put turning that switch off inside the same routine, again, so it will be ready for the next time.
- now you just have to authorize that switch for use by Echo. So go to the smart apps tab under automations, select the alexa smart app, and make sure your new virtual switch is authorized.
Then tell echo to “discover new devices” and you’ll be ready to use your new switch! Which in turn will trigger your routine, no matter what the routine does, echo won’t care. 
You can also use this method to daisychain routines by having the first routine turn on a virtual switch and have that switch coming on automatically run the second routine. So you could fold a whole bunch of your existing routines into your arm/disarm routines if you want to do that as well. Or you could have each of your existing routines subscribe to the same original virtual switch coming on. Just depends on what you need. Again, echo will only know about the original virtual switch, which is the one you will tell it to turn on. It won’t know about the routines, So it won’t care what they do.
(We used to have a much longer FAQ for this because you used to have to add an additional smartapp in order to run the routine when the switch came on, but now that is built into routines themselves, so now it’s easy. Create a switch. Have the routine automatically run when that switch comes on. Authorize echo to use the switch. Done. )