Most tuners reduce intake restriction to enhance performance, seems to me, then make an effort at optimum jetting for the air/fuel ratio they want at their typical operating altitude.
No reason one couldn't have a variable-restriction air intake, I suppose, but . . . why strangle those extra horses (available from a less-restrictive air intake) at lower altitudes?
In the Bad Old Days Of Carbureted Automobiles, tourists drove their family busses from the seashore to Denver and maybe even to Pike's Peak, without mixture adjustment. An inevitable power loss at altitude was present, and--air/fuel ratio not optimal for high-country touring, but--for temporary/incidental travel, motorists muddled through, without carburetor alterations. (The high-country "natives" might make some lasting changes; Ford offered high-compression "Denver" cylinder heads for its flat-head V-8's).
The CV carburetor performs some limited altitude compensation on its on (a lessened Bernoulli effect from less-dense air at altitude results in less slide/needle lift at the same intake velocity/rpm, with corresponding mixture fuel-leaning). Not a great deal, but--I'd bet you could "make it through the night" with a sea-level tuned KLR in the mountains.
Tweaking the fuel screw might improve starting and idle performance, but the needle/needle jet and main jet dominate mixture beyond a quarter-opened throttle.
Then, the "Dial-A-Jet" might be the answer to travel with high vertical relief. The device permits jet-size adjustments externally to the carburetor. No personal experience, but--an interesting concept.
What the heck is a, "Dial-A-Jet?" Unless you've take tne lifetime blood oath NOT to EVER click on a link on a motorcycle forum, click here: