Oh, ok. On the grip if you can use a regular overhand grip all the time until you need the over under that will strengthen your grip a whole lot more. So maybe if you can only do a rep or two with the double overhand and then switch to over-under. Then next time maybe you can do more with double over. That is going to keep the grip strong and then give you the OPTION of going to the over-under in the future only when needed which will keep you away from the straps since the over-under is MUCH easier. Basically everyone should be using a double over-hand as much as possible in order to keep the grip strong.
So on the rows it sounds like you are simply trying to compensate. I don't know how you could be standing up with a horizontal back though
. I'm not sure I get you on that. In any case it just sounds like a reaction to a weight that's beginning to stall out on you so you'll probably need a backoff soon.
My earlier comments were assuming that you lower back had become a limiting factor. But that doesn't seem to be the case.