I done my time in the Tyre industry at HQ for a major Auto company,I would never use this on any pavement or above 20 MPH. I would not spend a dime to buy this product. This is one of the reasons for a matching full size spare tire.
If your off the pavement even if you do not lower your tire below the vehicle manufactures recommended pressure; #1 If you go over a rock, log or a pile of dirt your tire can flex beyond the normal highway sidewall flex. #2 The air pressure going through the cut is pushing the patch way from the tire. Every rotation of the tire the side wall will flex the adhesion causing it to get weaker. #3 All of this is if you have the tire spotless and no hairline cracks in the tire itself or raised rubber on the sidewall to make a seal.
I would rather trust 5 string plugs then this one. I do not recommend putting in that many plugs, but this is I believe safer then the "Glue Tread".
My advice if you travel without a spare tire, your gambling and the price you pay should you need a spare, could be a lot more expensive then the patch (if you want to call it that (I would not)).
Invest your money into learning how to patch a tire from the inside. You should have a jack in your vehicle (that is one piece of the kit), 2 or 3 tire irons part #2, The patch and glue is # 3, tire cleaner and a scuffer #4, a little soap and water #5, Get training so you know what to do with these #6.
To answer the question before it is asked! If this is used off-road only then when you get to pavement you will need to replace the tire with a spare, or have a new tire brought to you. You will need to change the tire at some point. So having a spare with you, you do it at the first stop to install the patch or later when you reach the pavement
I will say that I have never used this product, so I may be all wet. But with 47 years of off road (4X4) driving I do not trust this product with my life. The reasons I say this is, the tire carcass has built in cords built around the tire and not glued on. There is a reason that the U.S. Federal Highway Transportation Department regulates and inspects tires and they have to meet the safety standards before being allowed on the roads.
I will let someone else be the guinea pig.