Most trailers with or without LQs use a battery as a power source for its lighting. Since it is not advisable to use your truck as a power source, your trailer usually has its own battery(s). Batteries have a limited amount of storage capacity. If used as a 12v power source, they can power small lights for a decent amount of time; several hours. If you were to add an inverter and try to power an ac appliance, its capacity would only be a few minutes of operating time. Some of your gas appliances are dc (battery) powered and once they are running do no use a large amount of electricity.

The second source of electricity is an outside ac furnished by a power cord. This powers air conditioners, microwaves etc. This source is also commonly used to charge the battery and when converted, sometimes also runs the 12 v lighting and accessories.

The trailer doesn't care what the source of ac power is, as long as it's a regulated voltage. Some needs such as computers require a more filtered voltage, but most appliances work well on a standard sine wave. Some generators get their voltages and frequencies through different methods, basically the more expensive units give a better result.

I don't know why your friend requires a direct generator connection other than to lessen line losses. I've been to many different venues where generators are commonly used remotely. They've been in truck beds, on hay racks, sitting beside the trailer or even mounted inside tack areas. They are used when there is no power available or when the show grounds charge an unreasonable amount to hook up. I see no reason why your power cord can't be plugged into your generator as long as you don't exceed its rated output. Many others do it on a daily basis.

BOL  Gard

Correct. 

Correct.  Put in 12v lighting and a deep cycle battery.  Use the battery for the lights and the AC source for all else.

I am planning on getting a generator with electric start. It's going to be mounted in my hayrack and I know that if I go with the "yank" start, I will eventually end up tumbling off the top of the trailer. I am HORRIBLE at starting those things.

Of course, I'm not seeing the real benefit (though I am sure there is one) with the comment made about "not having to go outside on a cold morning to start the generator". If it's that cold, wouldn't it already be running to operate whatever your heat source is???

I think I am going to go with 110 lights and then leave the one current light & switch that came with the trailer in place somehow. It operates off the truck battery. If I am somewhere and not plugged in, that light will be sufficient for me to do whatever it is that I need to do. Otherwise, I'll be plugged in and all the other lights and stuff will be working. Does this sound okay???

It would be best that no lights in your trailer draw power from your truck battery. If you forget and leave them on, there is a possibility that your truck may not start.

Most generators have a limited gas supply and are not run continuously all night long to keep you warm. There is nothing more aggravating than trying to sleep at night with a neighbor who is running a generator. Buy and install an automotive type of muffler and you will have more friends.

BOL  Gard

I have yet to go to a rodeo or barrel race with a quiet time.

This is true, but with a roof-mounted genset, you'll WANT to turn it off when you hit the rack.  Not to mention being a good neighbor to your fellow campers is always appreciated.

Okay...more questions.

Can my water pump (and maybe water heater) run off 12v?? Just enough to at least wash my hands/face without needing the generator? Even better would be if I could take a shower without needing the gen.

BUT will the batteries really have enough power to run a whole shower (5-7 minutes -  I'm quick).

We aren't doing propane so I guess it will be no showers without running the gen. I don't tolerate COLD showers too well (except in the middle of summer).

So to go with battery power, please add anything I have left off:

batteries

battery box

power converter thingy

No propane means no hot shower.  What Retento says - serious amperage is needed to heat water with electricity. 

Shower in a can will be your friend.

To install an electrical system in your trailer, will involve many components and a knowledge of ac/dc electricity is necessary. After that is completed, you will then have to know about and have the necessary components to install a water system. If you want hot water you will need a 110 V power source or propane. It can't be done on 12 v alone.

It would take many pages and hours of typing to describe all that is involved. I would recommend that you go to your LQ  installer, tell him what you want/need and have him build a system for you. What you want and need to do is not a matter of simply connecting a terminal to a wire. You will want a finished product that is both functional and reliable.

Gard