Hi guys, I bought a Base 2up spark about a month ago and it was the only one I could find so I didn't really have any choice anyway. But I am now starting to think it would be really fun to be able to use it to tow and I was wondering if I can just buy the 3up model seat along with the two extra seat supports that are required and make it a 3 seater. The only other thing I would also need is the hull extension for increasing the weight limit but I am not really able to find it in the parts lists online. Has anyone else looked at this? I am just wondering which is the hull extension part that I need to buy as well.