You might run the fridge and A/C at the same time, but I bet that 3000 Watt genset won't start them both at the same time. That water heater may have to be run all by itself, this all depends on the wattage of each appliance. Another thing, is this 3000 watts continuous running or 3000 watts start up? Alot of 3000 watt advertized generators are only rated at 2800 watts running, the 3000 number is for start up.

This page will give you an idea of how much wattage is needed for each appliance... http://www.cumminsonan.com/rv/select/wattage/

An all electric LQ will preclude your ability for primitive camping without your generator. You will not be able to use any appliances without running the generator, so you have to decide if this is the type of use you envision. It is less expensive to build an all electric LQ, but by adding propane and batteries, your choices of camping styles are greatly enhanced.

Do you want to mess with the generator, extra gas and the noise whenever you want to use your trailer?

Most LQs are equipped with a 30 amp shore cord. This allows a maximum of  3600 watts of power that is available. Your air conditioner, depending on its size, can consume up to 1700 watts running and more on start up. This only leaves 1300 watts left from your 3000 watt generator.

Your generator has several specification, two of which will be: a full load with continuous running, and a surge load, which may be its maximum out put. You cannot run a generator at its maximum rating for any length of time. Running at higher outputs will drastically increase its fuel burn, operating temperatures, and decrease its overall reliability.

My choice of LQs will always be a three way power supply; gas, battery and 110v.

Gard

That's a nice unit...!!

http://www.hondapowerequipment.com/products/modeldetail.aspx?page=modeldetail&section=P2GG&modelname=EU6500ISA&modelid=EU6500ISA

Really think hard about how you will you use your trailer, and if there will ever be a time you can't run your generator or can't plug in.  The primary use of my LQ trailer is for horse shows, where RV hookups are the norm (water and power).  However, there are a few shows I go to where hookups aren't available.  It is a pain to have to run the generator for power.  In your case, you would have to run your generator all the time to keep your fridge working.  With no propane, you won't be able to run your fridge going down the road either.  So you will either have to use your fridge as cooler while traveling (with ice in the fridge to keep things cool), or hope it cools down quickly when you get to where you are going, and then load your fridge, and make sure all perishables are consumed before your trip home, or transferred to a cooler.

If the trailer you are considering is truly all electric with no batteries, you will have no lights in your trailer when its unhitched or the generator isn't running.  You will have to be hitched up or have the generator running when you are packing and unpacking for each trip to have lights in the trailer.   

I am rarely without a hookup when I use my trailer, but I wouldn't want one without propane and batteries. 

I camped for 4 years with a friend that had an all electric trailer.  She has an Onan generator, I think a 3000 or possibly the 4000.  I do know she would start it, let it run for a minute, then turn the AC on. She does have a 20 gallon gas tank mounted under the GN - so she is able to carry enough gas for a weekend without worrying about it. 

The biggest issue I found with this system is that the fridge becomes a cooler - you have to fill it with ice packs as it's not cooling when your'e driving or the generator isn't on.  She does have 1 battery that runs lights, fan, etc  

My camping group doesn't allow generators from 11 pm to 7 am - so that leaves alot of down time if you're camping without electric, which is very common for us.

When I bought my LQ - I made sure I got one with propane - only way to go in my book.