Hi Johnny and
to the forum.
I think two 10kW motors is way too much power for your proposed tank, and I'm also concerned that there may not be sufficient torque applied to these motors to provide effective throttle control, as the VEC controllers tend to use direct torque control instead of motor speed control.
The following examples are based on information taken from the 48V data sheets for the
10kW and
3kW motors combined with a 12" effective wheel diameter:
A pair of 10kW motors with a 100:1 reduction gearbox would produce 10kW output @ 86% efficiency, and would result in a combined forward force of over 3.6 tonnes @ 1.25mph
(maximum speed would be 1.69mph).
A pair of 3kW motors with a 50:1 reduction would produce 4.1kW output @ 90.5% efficiency, and would result in a combined forward force of 670kg @ 2.8mph
(maximum speed would be 3.2mph).
As it is to be used in a parade, you should not need more than 3 mph top speed, and you are not going to need anywhere near 670kg of force to propel your tank along at this low speed.
A pair of 3kW motors can easily produce 11hp output, which should be ample for your project.
A pair of 3kW motors and VEC200 controllers is $1036
A pair of 10kW motors and VEC500 controllers is $2486
A pair of 3kW motors weigh 14.6kg
A pair of 10kW motors weigh 34kg
According to my calculations, a single 3kW motor with a 50:1 gear reduction should be able to propel a 1000kg vehicle up a 30% gradient
(16.7°) at a speed of 2.79mph.
As ride on lawnmowers/tractors have relatively high rpm motors, but travel at reasonably slow speeds, they might be a good source for suitable gear reduction units. Most will even be equipped with a number of manually selectable gear ratios which could be used for fine tuning the available speeds.
Another option to consider would be several sets of 12" wheelchair motors with built in gear reduction to drive the tracks directly:
Hopefully this will give you something to think about.
Alan 
