1) I use 12V LEDS all over the back yard and drive it with 150W adjustable Universal Laptop charger in the basement and allow >2V drop on AWG16 wire with ground wire strapped to Return wire. and get to the end stripLEDs with 14.3V You would need AWG 8 as Dave computed or mount the PSU above the LEDs and route AWG 16 3 wire extension cord.
2) I also use Surplus scrap boards used in Ambulance/Police cars, but I cut the 16x1 arrays down to 5x1 for running at 14.5 to 15V at slightly less than full power for garden lights.
3) Judging by my 10yrs with similar LED experience at this density of power LEDs per sq.in. of aluminum clad board space, I would expect for these LEDs at 25A to burn fingers and age LEDs faster, unless there is a good wind. So I would recommend reducing current to 19A as follows;
4) Meanwell also makes 13.5V 19A CC power supplies. $63 usd
http://www.bravoelectro.com/mean-well-sp-320-13-5.html
5) Your backyard neighbours may complain about the light glare. A 90 deg downward angle may be what you had in mind.
6) Choosing a supply with remote control or dimmer might be useful.
My former house garden lights all in parallel from CV used 4S Led Alumclad board on 12.5-13V with no noticeable difference in dropped voltage and 20% less power at end did occur. (It is hard to notice unless side by side.)

7) Your backyard will look like stadium lighting. with 288 W.
but I suspect at this price, they will be bluish 6000'K rejects.
Engineering Calculations
If you start with 13.5V and want 12V at Lights. Consider this.
288W for 96LEDs @ 12V translates to an array of 4S24P or 24 parallel ccts. of 4 series LEDs (~3V/LED)
Each 3W LED will have an effective series resistance (ESR) of <1/3 Ohm thus *4/24 = 56 milliOhms for the light bar.
Thus for a 1.5V drop @25A, the wire dissipates 37.5W which is 13% of the load power and requires a resistance of 1.5V/25A=60 milliOhms (or <=AWG 8 for your length).
If you want max brightness but calibrated for a load at 12.0V, you might have to go AWG 6 or shorter cable so you have some margin for error. Crimp contacts have to be done perfectly to achieve < 10 mOhm.
A PSU inside near the Lights is the best choice for you.