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You are right to be concerned over the long and frequent duty cycles. Generally speaking I would try to stay within the 66% to 75% capacity of the generator especially for a long duty cycle in a hot place, and go for diesels unless diesel fuel is really not available.
I would go for something factory built - may sound obvious but you can still go out thinking to buy something you recognise as a generator and eventually be confronted with units cobbled together locally from random gensets coupled up to old Lister hand start engines.
I can’t work out the size properly from what you have written, there are a few too many variables in power consumption but everything that is to be attached will have info on it somewhere - estimate about 20% of these numbers for anything with a motor or transformer in it (pumps, fridges AC units etc) and then as above rate the generator to run at about 66 - 75%.
Getting two gensets the same can be useful, and may make service parts and familiarity easier, I would try to get something common to the region and as good quality as your budget can accommodate.
One thing: Once you set up long term generators people will come out of the woodwork with reasons to plug in, so either be strict or make sure you can accommodate the increased load when you feel generous to requests (and keep control of the system, no leads running off across the bush, there is no telling what people would consider reasonable use).
Lastly, gensets can be noisy (and usually are). You need to secure them and block the noise but not confine them or you will reduce air circulation and cause yourself problems. I am sure the RedR handbook will have a few pages on how to muffle a generator without burning down the house…