It looks like you're from Iowa, and if your son is willing to pee outside, standing up, at this point in the year, I'd say go for it! My oldest learned to pee outside, off our deck, when we lived in Washington state. He was so excited to go pee off the deck that he DID it, and it was not a hard transition at all to get him to pee in the toilet. He WOULD pee in the toilet, if he had to; he preferred to pee outside. In my opinion, it taught him to listen to his body and know when he had the urge to pee. Admittedly, we lived in the country. But now, we live in a subdivision, and my five year old son still pees outside when he's too busy to come in (and so do the neighbor boys, who are also 5). Depending on your neighborhood, you might be surprised at the number of parents-of-boys who have taught their boy to use the toilet that way!
Edit: I just saw your So what happened? My son is 26 months, and has been peeing standing up on our regular toilet with a plastic step stool for a number of months (not regularly; just occasionally before bathtime). Yes, it's awkward. We had to push his bottom in to get him to pee in the toilet, and the bottom line is, you have to choose whether you want to toilet train the easy way (letting him stand), the hard way (forcing him to sit, since that's not what he wants) or not at all (I have a friend whose husband is such a neat freak, he put their three year old back in diapers because he dribbled down the side of the toilet). Bottom line: yes, you'll be cleaning. A lot. Even my five year old has entirely missed the toilet on occasion (in the middle of the night) and I've found a HUGE mess of pee on the floor! My toddler doesn't have a good enough stream yet to get IN the toilet, but he knows what to do, and that's important to me. I just get out the Lysol wipes. Also, now that my two year old is a little older, he gets up on the stool, grabs the seat and the lid together with both hands, and mostly gets pee in the toilet. Although...if he is at all distracted, as he was yesterday, he turns, and the pee goes all over. If you have a rug anywhere close, I'd suggest removing it for potty training. You could try sitting him on the toilet facing in; my mother did that for my son when he was visiting her house, although he doesn't have strong feelings about peeing one way or another.