Hawaii is at 21°18′41″N, 157°47′47″W

Both mountains are tens of miles from ocean and they both have towns down range.
From what RL says about the roads they probably wouldn't be big enough or straight enough to get +100' long rocket up them. It seems to me to would cost billions to just improve the road- and since you don't want to add further developments in area the billions of dollars spent would only be for this launch site.

For a private launch site it would seem to be pretty close to impossible, if public- there is already KSC and at similar latitude. Building another KSC like launch site would cost tens of billions if not a hundred of billion if you include decades costs.

If you going launch to GEO from 21°, it costs around 1.5 km/sec to change the inclination- and as guess Sea Launch from equator would better even if the mountain was 30,000'

Caution excessive wordage ahead:

I was going post this as additional note but it's vaguely related to this:

[[Regarding what said: "Having a launch pad at 10,000 would mean higher efficiency from the rocket because there was less atmosphere."
Relevant facts:
Atmospheric pressure is about 10 psi at 10,000'- almost a 1/3 less
And between 15000' to 20000' it's 1/2
and about 1 psi at 60,000'
http://www.engineeringtoolbox.com/air-altitude-pressure-d_462.html

A couple examples of difference between sea level and vacuum:
"Atlas IIIA:
Liftoff Thrust: 2 600.000 kN (584 500 lbf)" so that would at sea level atmospheric pressure.
Same engine in Vacuum:
Thrust (vac): 4 148.722 kN (932 670 lbf).
http://www.astronautix.com/lvs/atlsiiia.htm

Saturn V:
"Liftoff Thrust: 34 030.000 kN (7 650 240 lbf)" so that would at sea level atmospheric pressure.
Same engine in vacuum:
"Thrust (vac): 38 703.160 kN (8 700 816 lbf)"
http://www.astronautix.com/lvs/saturnv.htm

With Atlas IIA there seems like there is a significantly bigger difference in performance between sea level and vacuum of space than compared to Saturn V. The difference may have something to do with Saturn V being a three stage rocket- it being a older rocket design, and/or perhaps several other reasons.

So launching from 10,000 ft you get different results depending on rocket and if you were launching from 10,000 ft you would probably use different rocket nozzle than if launching from sea level [and same applies to launching from a pipelauncher because it will rapidly get to higher elevation].

Take a rocket launched from a pipelauncher at 150 mph and compared to rocket launched from mountain at 10,000'- which one gets to 60,000' first?

If mountain top rocket has average acceleration of 8 meter/s/s for first minute it takes 61.7 seconds to reach 60,000'
In 61.7 seconds traveling at 150 mph [220 ft per second] you go 13574'. So if both rocket used same amount of fuel and had same acceleration the pipelauncher launch would reach 60,000 before mountain launch- but I didn't include the improve rocket performance due to the less atmospheric pressure at 10,000'.

Breaking into shorter time
With the lower altitude from pipelauncher if you assume an average of 6 m/s/s acceleration for first 25 second and starting 1000' above ocean, you get 6500' in 25 seconds from pipelauncher and 1875' from rocket acceleration so total of 8375' in elevation.
Now say we give the mountain top launch an average of say 7 m/s/s acceleration for first 25 seconds [due to better engine performance]. So at end of 25 seconds it's reached 12187' in elevation.
So at end of 25 seconds pipelauncher rocket is traveling at 485 mph. And mountain launch is traveling at 391 mph and both have same amount fuel. ]]

If you interested in private launch, or are generally interested in lowering the cost of launching rockets, a pipelauncher is vastly cheaper than other kinds of launch pads.