How about launching the personnel carriers this way?

https://en.wikipedia.org/wiki/Laser_propulsion#Laser_Thermal...

Then send cargo up that's hardened for 30g in a vehicle launched from a 20 mile long mass driver that's tilted 45 degrees. We should be able to build such a structure by starting several miles underground, then building up the side of a mountain. 30g over 20 miles yields a final speed of about 9735 miles per hour. With a boost like that, the vehicle wouldn't need a 1st stage and could probably get to orbit without staging.