You are already getting good advice here. The only other thing I would add is that if you need to back the trailer up hill/grade the surge brakes will activate and drag a bit. Most people I know have a block of wood cut to wedge in the tongue to stop the brakes from activating. A 2 5/16 will be quieter and smoother than a pintle hitch, and work better with a WDH. Either will be capable of the weight's you describe.
Most modern surge brake systems have a solenoid that is powered via a fifth wire that is energized when the backup lights come on. That’s why many boats come equipped with a “Flat-5” pigtail.
Older iterations commonly had a bar that you manually flip to block the tongue compression.
Even older ones have a block of wood shoved in them, as mentioned above.
Surge brakes, when operating correctly, are great. The tongue “squishes” in when you tru to stop the tow vehicle, because the trailer wants to keep moving forward. Just like a brake pedal, this tongue compression forces fluid to the calipers and applies the brakes. Quick stop? Lots of trailer brake. Nice, easy stop? Gentle trailer brake. It’s all relative to how fast you’re attempting to decelerate.
If you go with an electric controller, I’d recommend the Tekonsha P3. It is programmable and works like a dream after the initial setup. That part takes about 5 minutes, max... The nice part about the P3 is that it utilities a decelerometer, which means it senses how abruptly you’re trying to stop. This equates to a very smooth and fluid application of the trailer brakes. Just like a well set up surge system, hard braking on your end will get you a lot of trailer braking.
If you had a newer Tundra, the brake control output is dependent on how far you’ve pushed the brake pedal. It’s supposed to work like an extension of the pedal, but is inferior (IMHO) to the P3 in every way except the best little display on the dash...
Which ever way you go, get help learning the ropes. 8K pounds, plus trailer, is nothing to joke around with. Go to a reputable tow/hitch dealer to make sure you are getting the right equipment, and that it is all operating correctly. Our trucks have no problem getting that mass going, but stopping it is a different animal altogether...
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