Well Sir, without sounding like the inevitable "I told you so", in all reality, this IS your fault. Now, I'm definitely not jumping on you here. What I'm saying is, you've most likely been on the forum for a while, and probably visited many sections of it. People often ask about many types of possible intended toads on this section and, even the other sections that are not really toad related. And the most noted answer is to those folks who ask about a certain possible toad is: "Did you check the owners manual for instructions for flat towing"? Another answer is: "Did you check with the Dinghy Towing Guide of the model year you're intending on purchasing"? Many will answer using Remco as a guide but, I've seen them wrong, more than once. So, it's up to the individual to use them.
So, without further "bashing" on my part, my answer to your situation might be something along these lines.
Yes, you are ultimately responsible to purchase a toad that is "flat towable", not any one else, including any facility that will be providing any service of installing of any parts/components of towing. They are primarily only there to discuss what is to be used/sold in terms of parts and components for your vehicle. There are many service writers, receptionists, parts people, phone answerers, that cannot tie their own shoes. So, expecting for someone on the other end, to be real competent in a situation like this is, for the most part, not really real.
But, on the other hand, yes, there are folks, workers, owners of RV repair facilities, techs, etc. that are really on the ball and, quite possibly might have stopped the entire install of all your components, because they're familiar with those vehicles that can be flat towed and those that can't.
The techs that installed your equipment, most likely was just following orders from a shop supervisor and, that shop supervisor never thought to ask, "Is this flat towable" or, mention to you that, "You know, this vehicle IS NOT FLAT TOWABLE, ARE YOU SURE YOU WANT US TO INSTALL ALL THIS EQUIPMENT?
To be up on all the latest, in terms of knowing what vehicle is flat towable and what ones aren't, is up to the individual that may be the shop forman, or shop supervisor. However, it may not be part of their job description. If they take the time to learn the majority of them, it's most likely just voluntary on their part.
Now, as to your next move. Since it really is NOT their position to tell you that your rig is not flat towable, you will most likely have to pay all of what's required of you for the work done. I'm certainly with you on the removal of, and re-install of, the drive shaft each and every time you get ready to tow or, want to disconnect and use the toad. That sucks big time. Try doing it in the mud, or on 130 degree hot pavement, or, at 10:00 or 11:00 at night when you just arrived at your camp sight and the entire camp is asleep, YEAH SURE!
Now, one more move that you COULD think about is, the addition of a drive shaft disconnect system that some are still using. I'm not a fan of them but, apparently some are. I've read many reports on here an other forums from folks that had them and say: "Never again", due to the fact that the mechanism is a splined set of teeth and, those teeth get all gummed up with road debris, grease, mud, gravel and more and, when it comes time for you to put it back into driving mode, the mechanism won't move due to all the gunk that has accumulated on the two moving components. Those folks have had to continuously get under there and clean the splines to allow for them to "engage".
Well, that's not for me either. I've been down on and, gotten up from, a creeper probably , in all reality in my life, more than several thousand times, I don't plan on doing any more than I have to.
So, what to do??
1. Remove all the components that were just installed and,
2. Sell that vehicle and possibly find one like it that is "Four wheel drive and, flat towable" and, if possible, re-install those components. This option will be quite expensive.
3. Get the drive shaft disconnect installed and, possibly have to deal with its issues.
4. Remove all the components that were just installed, sell them, and get a trailer that will haul the vehicle.
5. A dolly might be in the future too, I'm also not a fan of those but, it's a preference thing.
Good luck, and, sorry for your dilemma.