Addressed so far:
New Clutch and associated hydraulics
New brakes
New valve cover, ignition coils, plugs, PCV
New oxygen sensors to fix service engine soon light
New gear lube in transmission and differential
New A/C compressor
New shocks/struts ... bought NAPA without thinking; Should have gotten KYB.
All parts either genuine Nissan or best available

Am I missing anything to make this vehicle worry-free for the next 12 months / 12,000 miles ?

I am planning a road trip from DFW to Cancun with the intent of avoiding any vehicular surprises.

 

You might want to unbolt the cross member in the front and make sure the rad support is still in good shape. If it's a Texas car you're probably fine but it's worth a look.

The rear calipers are known to seize also.

 

How many miles do you have?

Check out the shifter cable support bracket that's bolted to the side of the transmission. I've seen a few reports of failures, leaving the transmission stuck in whatever gear (or neutral) that it was in when the bracket broke. I recently swapped to the 6th gen bracket just to be safe and my original one appeared fine with no cracking with ~240k miles .

Replace the small little plastic pads on the brake and clutch pedals that press against the various electrical switches (brake switch, etc). They're known to deteriorate and cause issues such as brake lights always on, no cruise control, etc.

I'm on my third alternator (replaced at 65k and 220k) and my power steering pump went out around 245k. All other drive accessories are original, but I see you've already replaced the A/C compressor. Did you install new drive belts at the same time? If not, did you make sure you installed the belts in the same rotating direction as they were when you removed them? Swapping direction can shorten the belt life.

The OEM radiators with the plastic end caps are known to fail. I'm on my third radiator and this one is a Mishimoto all aluminum one just for peace of mind. My first failed at around 120k and my second did not fail before I swapped it out at 240k to the Mishimoto.

Honestly, most of these you can avoid and most likely be fine...but if you're nitpicking, well here are some additional things to check. For the most part, these cars are pretty simple and reliable. The only thing that's ever left me stranded is the alternator at 220k when I was in Houston. I replaced it in my friend's garage with a unit from Autozone and was on my way.

 

I have 139K miles on it. It seems that the previous owner couldn't afford to maintain it and parked for years. It's scary to spend $18K on a $5K car. If you want a non-fragile 6 cylinder, MT car, all my options were worse than this one. My hope is that this car will outlast me.

 

cats

 

I've had mine since 2004 when I was 16, and I hope the same thing LOL. I still love to drive it.

 

I am the original owner of a 2002 dark blue, gray leather interior, SE MT and the car has always been a blast to drive. I take my 14 Boxster S to the track but I have so much fun with the 6MT Maxima that I will never sell it. Still going strong at 165k - always shocks people when I go WO in 3rd gear. Still the original MT gears but the clutch was replaced at 150k.

 

So Crazy. I also tracked my 2014 6MT Boxster S. Sadly, I sold it this year, but it was definitely a fun car while I had it! I replaced my clutch at 185k just as preventative maintenance, but the disc looked shockingly good when I removed it. Definitely could have gotten to 200k.