Re: How do YOU mix 50 gallons of syrup?
Lots of similarities isn't it! Seems like a LOT of fun things involve, sugar, burners, large kettles, tubing and hoses, LOL!!
Speaking of which, those that are handy could rig up a HARMS or RIMS type system for heating water. They are used in beer brewing, basically a 1½"-2" copper tube with a water heating element installed in it with water recirculated until the desired temp is achieved. One could also use a portable instant on / on demand type water heater. I have a small one, but it only puts out about 1.6gal/min of ~120°F water. Some models will do 5+ gal/minute of 120°F water. You could also invest in a pump used in beer brewing as well, they are magnetic drive and can run continuously even with boiling temps, but should work great on cooler syrup to transfer to buckets, etc.
I only make small batches, so I use my Blickmann 15gal SS kettle and burner to heat up enough water for the batch I'm doing, then dissolve in the sugar and mix with a large SS spoon. This winter I'm thinking of converting one of my SS kettles to one with an integrated immersion chilling coil to chill it's contents quickly, use it for making syrup AND beer....hehehe, gotta love multipurpose tools.