Hey Fritzcat,
good research and deep thoughts. So I am just going to answer in a piecewise manner:

1: we didn't do any quantitative testing at altitude due to the logistical challenges involved and high expense of doing it, but we have been busy on the qualitative side of things. People within the company and riders of our boards have ample experience with island hopping and flying with unpressurized cargo holds and the boards do fine. There really isn't enough internal pressure (or gas for that matter, think low n value) in the board when it is made so the it would take more extreme conditions to reach dangerous levels. Plus when you fly in such a way, typically the board is exposed to reduced temperatures, and when you toss a decreasing T into PV = nRT and assume the volume is a constant, then clearly the internal pressure will be reduced as the board cools (don't confuse the P in this formula for external environmental pressure). I think the two come very close to offsetting as we have never seen altitude related damage to any of our boards. Just an FYI, high heat is a far greater threat to the board than decreasing external pressure.

2: your house at 2800 ft is MORE than safe. I just drove through the rockies, cross country with a board and hit 12,000 feet and not a thing happened, other than snow in July (my summer).

3: regarding the vent....technically yes you can fill in the hole, but I personally wouldn't do it because the valve is 100% passive, requires no maintenance and we RARELY ever see issues with them. I mean rarely!!!! I think you actually increase risk of damage by altering a pre-existing valve.

Hope this helps!!

Yeah so long story short, way more important to keep your board out of HOT HOT HEAT.....not the band though, as they can be entertaining in doses.

Sounds good Chris..
As for the heat. I primarily see alot of board damage (all kinds of board materials ) from that factor alone. Its a no brainer, but people still leave the car windows up at noon with the board cooking inside...

well if you did that with a Sweet potato, after a while you would have a baked potato.....waiiiiiiit........

jejjejeejje