I've been smoking in bad weather for years (rain, sleet, hail, snow, temps of -20*F & below, and lastly, the ever persistent, relentless WIND) with both charcoal and propane fired rigs...none of which have been modded to include auto-temp control. None of mine will hold temps well if exposed to wind, or precipitation...they both will suck the heat right out of a smoker, though wind has the most noticeable impact. The simplest measures to prevent this are to protect the smoker from the weather, and with blocking the wind having the most effect on performance, that's where you want to start. Placement of the smoker on the downwind side of structures is often all that is needed, and will not only reduce temp spikes/valleys, but will most likely stop your flame-out condition as well. You may need to compromise at times, and move your smoker away from your ideal location.
You can engineer a ton of mods to prevent flame-outs and add an insulating layer to reduce temp peaks/valleys, but at some point you have to ask yourself if there's a simpler way, such as adding thermal mass to the interior rather than insulation to the exterior. The more complicated things get, the more room there is for malfunction or undesirable operating characteristics to occur, not to mention the added expense. Keep it simple...I'm one of the grandfathers of inventing things out of need, or the want for a little better performance, but I have also pulled the plug on some of my own ideas because they took a few too many turns toward getting complicated and difficult to engineer...just for the sake of answering the question "is it worth it?". Maybe I've softened-up a bit in past couple years, but now days I only do smoker mods if there is no other option available.
Best of luck. Keep your smokers warm and happy!!!