If you double close the seller will see the final sale price after recording. The benefit of the double close is so that the buyer doesn't see what you are making. I don't know what state you are in but the assignment should only be on the buyers side of the settlement docs, at least in Ohio which means the seller won't know what you are making.
I would not go and just offer without intent to buy. If it's a legit wholesale deal and you are buying deeper than 70% minus repairs and below, there isn't a hard money lender around that won't lend on it. Make sure you have enough cash to cover down payment and a few months of holding costs, not just 10 dollar earnest money. If you actually can't get the lending than at least you tried and were not just trying to waste the sellers time or worse yet leave them in a worse situation than they started in. If you have to close, just list it on the mls for a dirt cheap price and it will sell in no time, you will actually probably make more. If the lender declines you, you locked it up for too much. Hope this helps! It will also keep you above board