Google Stainless Steel Mixing Paddle, there are a number of stainless steel long handled (up to and over one metre in length) paddle-ended cooking/stirring paddles made for large cooking establishments etc where large quantities of food are cooked. They cost from approx £20 to over £100 depending on which item. Google mixing paddle and you will find various suppliers and varieties to choose from.
Oh they exist, I've certainly found some that might work. Just not found one that made me go "ooh, I like that".
My mash tun at home isn't that big (compared to the one at work anyway), but it's big enough for the mash to break lesser spoons.
Julia