Again, I need some of your advice!

I’m now looking for a cheap water gun, avaliable in Spain, where I haven’t found the Water Warriors brand. Here we only have the newest Super Soaker series, and it seems difficult to buy the US waterguns from here..!
For boat water wars, I’m looking for a high range, high output and highly intimidating watergun. I have no problem with refilling it, (because of the river). I’ll pick only one, because most guns are for 4-5 meters of distance (15 feet I guess), and we want to shot first (we will have 10 people in our boat, everyone with a syn gun and a beach bucket).
Do you think the Super Soaker Hydro Cannon is a good option for us? I found it for 20€, and looks pretty good. Do you know if there are any modifications I should consider? (perhaps some to pump water from the river or something like that..?)
Thanks a lot!!!
PD: I created a new post here because I think this is the “correct” way.