No stupid questions on this forum. More than likely you will never get flamed for asking a question. Most on here, me included, would rather answer a simple question now, instead of have to tell you how to fix something big later, because you were afraid to ask.....
Now, back to the question at hand.
With a 7.3PSD and the 4R100 auto, yes, I would do the O/D Off button just like the IDI. I would make sure you have a good cooler on it, and good fluid. The 4R100 and E4OD are VERY similar transmissions, the same thing that makes one unhappy, will do so with the other. One exception to this, is if you are on a dead flat run, and the transmission is not "hunting" (you know - 3,4,3,4,3,4,3,4,3,4 all the time) you can tow in O/D. Some on here will say with a good converter, good cooling you can use O/D as long as it doesn't hunt. That is the main reason Ford says O/D Off for towing, it is "safer" as the transmission will not hunt as bad, and all that shifting causes heat, which is the problem.
Now, if it is a newer PSD, 6.0 or newer with the Tow/Haul Button. Hit the button and let the transmission do its thing. They are much different that the previous transmission. I know on my 6.0, it will use all 5 gears when it is in Tow/Haul mode, but the shift strategy and a lot of other factors are adjusted by pushing that button. It is just not a simple O/D Off switch.