When you have him sit on the toilet, spread his legs really wide and put him more towards the back of the toilet. Then have him put his hands in front of him for balance, on the front part of the seat. So he is kind of leaning forward. This will make his head go down a little so he will end up watching himself pee.
The leaning forward will naturally aim him down. Unless he is slightly erect (which can happen after a serious nap or in the mornings) there will be no spraying around. The learning to watch his own pee will fascinate him...you can even build that part up (look at the bubbles! or whatever) so he begins to get an awareness of where his pee is going. He is old enough that if he pees on the seat you can hand him a bit of toilet paper to start wiping it up. (Which he won't do well, but it is the habit you are building.)
If you have a round toilet instead of an elongated toilet then you will have more struggles simply because he is not yet controlling his stream and probably won't for another year. But this position really helps.
I've potty trained four boys and my opinion is that until they have an awareness of where the pee is going, you don't want them standing. You want them to learn to watch. Because if they are not watching, it will not matter if they are 7 or 8, they will still look away and pee outside of the rim while standing. (My husband jokes my older boys, "You have to be a man to be able to pee and not look. And you, my boys, are not yet men.")