DS has been TT for just over a month - he wees and poos on the loo and sits down for wees. I want DH to teach him to stand up soon so DS can wee while we are out and about (under a tree if necessary if we are not near a bathroom), but for now he is successfully TT'd so there is no rush. Also DS is very short, so he'd need to stand on a stool to reach his willy into the loo anyway

I think your instincts are right Leckert, you know your DS's comfort level. Also, We used the 3 day method, I have an ebook which is pretty quick to read through, we found it fantastic (a very supportive method based on rewards)