Why would you buy an extra phone if you just mail the keys around the internet anyway. True they encrypted, but you can generate an offline wallet with any old pc, no need for a new phone.

Id just get a script (preferably from github) that does the key generation for you.
#1 Download script
#2 verify download
#3 copy via (new) usb stick to old PC running a live linux from CD/DVD
#4 generate keys
#5 print
#6 keep printed keys safe