The 2.5 gallon bottles in my humidifier are heavy plastic similar to LCI 5 gallon water cans, have sturdy built in handles, are rectangular, have a thin profile and weigh less (easier to move around) than a 5 gallon can. Just replace the spring loaded valve with a cap and you would be good to go.
Not cheaper if you have to by them new (about $25 each) but a "better" profile for storing/mounting in smaller spaces in a truck maybe.
For example: (2 built in handles)
Water Bottle for Bemis/Essick Air H12 Series 1B5060120
Not cheaper if you have to by them new (about $25 each) but a "better" profile for storing/mounting in smaller spaces in a truck maybe.
For example: (2 built in handles)
Water Bottle for Bemis/Essick Air H12 Series 1B5060120