How 'bout something like this. You didn't mention the model your Deere is, but if it's a lawn tractor I'd think 30 gals of water is about all you should pull - and maybe not even that much.

Here is a link that might be useful: 30 gal sprayer

""My JD does have a 12 volt plug.""

What Model JD do you have?
What do you use the 12 volt plug for?

I have a JD LT 155, and would like to run an air compressor from the battery. (Central Pneumatic Model 96068 12 vol 100 psi). I keep the tractor in a yard shed, and would like to be able to check and inflate the tires before I start mowing without running the battery down and not being able to start the tractor
______________________________
I would also be interested in the responses to your question about watering.

I have thought about some type of towable tank but had always thought about, a gravity flow system to water the trees and bushes. With my tractor (See above), I was also concerned about the weight. At 8.3 pounds per gallon you could quickly over load a lawn tractor.

Based on the recommended trailer JD Model 7 which is 7 cu ft. about 700 pounds. or about 80 to 90 gallons. (these are estimates not absolute)

A viable method without an electric PUMP is to use a sealed, pressure rated tank. The tank fills by connecting to a standard residential hydrant with a sturdy garden hose. The filling hose connects to the tank via a fitting port that has a shut off valve. This valve is opened to let water into the tank. As the tank fills, air is bled out through the dispensing hose by opening a valve on the tank. The tank needs to have a pressure gauge so you can tell how much pressure the tank is charged with. The gauge plumbing also needs to include a standard Schrader valve to add air from a source of compressed air.
The tank should only be filled to about 85% of its total capacity, to allow for a head of pressurized air above the water.
As the tank is filled with water from the hydrant and the water gets close to the marked full point, close the valve that is bleeding air from the tank. With that valve closed, the water coming in will begin to pressurize the tank.
When the water reaches the marked full point, shut off the hydrant and close the inlet valve that has the hose connection.
I recommend pressurizing the tank to the rated maximum, or to 60 PSI, whichever is the lesser amount.
Use a small 12 volt air compressor that you power from your 12 volt power jack to replenish the air pressure as you deplete the water.
Your dispensing hose should have its own valve at the tank and this valve should be on the very bottom of the tank to do the best job of completely emptying all the water.
Equip the dispenser valve with a fitting that a standard garden hose will connect to.
You can also fit a nozzle of your choice to the garden hose to spray the water as you choose.

This system is not exotic at all. it is the same type of system that is used on every "In transit concrete mixing truck" in the world. The water that the truck driver uses to wash down the chutes and things is sprayed from a water tank that is pressurized by the truck's on board air brake compressor.

There may even be some small trailerable tank systems already out there.

Not getting in the way of the pressurized tank or tank and pump discussion, but seems difficult way to go? Pick up the "appropriate" sized tank from TSC or equivalent, attach a drain hose to the drain fitting. Place the tank in a lawn cart, fill from garden hose. Haul to tree(s) and wet/soak down the ground (tree roots go no farther than the branches, BTW) around them. Believe me you'll spend more time riding back and forth than waiting for the tank to empty.

Just MHO.

Good luck,

Ev

For another different strategy,

As it has decided to barely rain here for a month and we are setting record high temps again I am watering.

My method is dragging out 220 or so feet of hose with three sprinklers on it, two cheap plastic spinners and one oscillating sprinkler. I can do three cheap spinning and one oscillating sprinkler but that is a good amount of hose to be connecting.

The cheap plastic sprinklers are important as they bleed less water pressure with their lighter mechanics.

Last year in our record drought and heat I learned to just water for several hours at a time so I only have to do each zone once a week.

Not sure what size trees your planted. The three footers from the conservation department can be sustained with a gallon every two or three days here. On the other hand, my thirty foot metasequoia needed the six hour area drench last year.

On the inexpensive side - I built a weight box for my aerator using plywood and 2X4's. then sprayed the inside with that rubber spray from Rustoluim.I was thinking of adding a water pump to it just to do like you. Buy a bilge pump for a boat about 500 GPH. They are 12V and only about $30 Wmart has them. Build yourself a box and put in a cart? Picture attached with water in it - about 30 gal. Look at my post about the aerator with more pictures.

Here is a link that might be useful: Aerator with winch

I buy 100' hoses until get there if longer than that I buy 1,000 roll drip main line I water 6 acre blackberry plants with 400 ft. garden hose.