How to measure the total current consumption in a system
The data sheet says the Toradex needs 17.5 watts from the 5V rail and 8.25 watts from a 3V3 rail. Total power is circa 30 watts including inefficiences of a typical switching power supply (that you'll have to buy or design).

If the sensors run from 5V (guess) and take a total of 0.5 amps that's another 2.5 watts. If the LEDs take the same (assuming a 5V drive and current limiting resistor) you are looking for at a total power well below 50 watts.

Your UPS has to supply this power. 

It beats me how you came up with 800 watts but maybe you can clear this up.