I have towed a 4,600# trailer all over the place, first with an E-250 van (V8), and now with my Chinook (V10). I find the Chinook tows it beautifully, with a couple of caveats. These may be old news to you, I realize.
1) Check your rear axle weight. My boat is on a tandem and thus can have a slightly lower tongue weight (5-7% vs. the usual recommended 10%). The tongue weight is around 350#, which due to Chinook overhang + good-old physics adds 550# to the rear axle. I have weighed many times while towing and not towing, so I know I'm underweight, but it's something to check. I do find the rear axle is the closest to the max vs. the other weight ratings.
2) If it's a tandem trailer, put some effort into making sure it tows level (not a Chinook-specific thing).
3) Trailer brakes are a good idea and may be required in your state. I have surge-activated brakes with discs on all four trailer wheels - stops very well (of course still drive conservatively when towing).
4) If you have surge brakes and are towing in the mountains, keep in mind that there is not a very positive "release" on the brakes -- so if you engage the trailer brakes near the top of the hill, they might well stay on the whole way down, thus getting very hot or worse. I slow up before cresting a pass, and then use engine braking (i.e. downshift). If you have electric-over-hydraulic brakes (cab controller) then this is not an issue. Related to this is that they say "don't go down the hill in a higher gear than you'd climb the same hill in." I also often click down out of overdrive (with the button) sooner than the automatic would. I can see hills ahead even though it can't. I keep the RPM's up above at least 2,000 RPM.
5) I installed a larger transmission cooler, but I think it would probably do fine even with the stock one.
6) I run a Scan Gauge II so I can keep an eye on transmission fluid temperature, plus engine coolant temp (and other stuff too, but those were the main goals).
7) Your rear Chinook tires will want a slightly higher pressure for the additional weight on the rear axle (I go by the weight/pressure chart for my size tires).
8) The wheel lugs on the trailer are likely a different size than the Chinook, so a different wrench/socket size.
9) If you hear an airplane about twenty feet overhead, it's likely just the engine (radiator) cooling fan. It's loud! Mine will kick in sometimes in hot weather when climbing. Usually it kicks in at around 200-202º F water temp, and then goes back off when it gets down to 197º (usually less than a minute). On a big climb, I'll turn off the Air-conditioning if I have it on.
10) My trailer is 8' wide, which is really nice as it just about tucks in behind the Chinook, yet I can see all four trailer tires/fenders in my mirrors.
11) I do have to watch things a bit if going in and out of something like a gas station with a big drop off at the street intersection. It's especially easy to drag the back of the trailer - I scout ahead and also go diagonally if I can. You may not have that issue with the extra clearance of 4WD.
The Chinook is a great towing machine for my boat. Even before I had the new front end/bigger brakes put on, it still worked fine due to the trailer brakes. I was comfortably under all the weight ratings, but I'm decently "underweight" to begin with (all Chinooks may not be though, from what I have read). I have also moved the spare tire to the front which moves around 200-225# of weight off the rear axle.
I have the manual rear step, so I don't need a super long tow bar. I do need to leave the lower step flipped up (storage position), and of course slightly step around the trailer tongue when going in and out. Door and all else works fine though.
If you have a long/tandem trailer, it will cut in quite a bit on corners, and also swing out due to the tailswing of the long overhang (didn't have that on my van). If you are launching, watch the rear axle (vent) and the generator so they don't get submerged (especially if someone goes by with a big wake just as you are launching
Coming down from Tahoe, if 395 works out, it's a nice towing road. Gorgeous and not crazy, traffic-wise, plus lots of places to pull out for breaks, lunch, etc. I towed from Seattle to south Texas a few years ago, but as it was December I "had" to go down I-5 instead (ugh) and I crossed over on Tehachapi, then took I-40 to 95 and down to I-10 from there, then I-10 the rest of the way, basically. But unless it's winter, I tow up 395. MUCH nicer. Of course you're already east of the Sierras.