You already have the germ in your mind, so to speak! I'm no expert but here's what I would do:
First, make a load list specifying capacities, voltages, etc.. Then write a description of each load operation; expected run times as well as expected time of day when those units are going to be used/not in use. From there you will see which units are running at the same time and the total demand for that specific period. There maybe more than one instance where the demand peaks. Get the max demand and divide by the total installed loads in your camp to get your demand factor.
HVAC units do not run heaters/compressors all the time, all heaters/ compressors cycle depending on the space controlled, the conditions outside, and the insulation of the space. Analyze a typical space/room and express usage as a percentage of the capacity of the HVAC. Just replicate those numbers you get on similar spaces. Then you can come up with a load profile which will help you calculate your demand factor.
In the absence of a load recording/monitoring equipment (especially if this camp is still in the design-stage), you will have to picture-out the worst case scenario in the electricity usage in the camp.
