TO know if the setup is OK :
first never exceed 50.000 rpm : so 4800 * 7.4 = 35000 rpm. You are far from 50000 (even at the begining of the run while lipo deliver more or less 8V = 40000rpm)
Now for you truck : you just have to adjust pignon / spur ratio tohave you motor not to hot (never exceed 60/65° in Clesius)