Lower moulding install on my 71 Fleetside?

[Faastone27]

So i just purchased new lower mouldings for my 71. The factory ones look ok but to make the exterior as nice as i can that really is the only thing left that has not been replaced. so i am looking at the truck and i don't think its going to be all that easy .To replace the the two small forward front fender pieces it looks like I have to at least take the inner fender loose to get to the backside of those? also the two small corner cab pieces it looks like the gas tank is in the way so do i have to remove it or ? Just looking for assistance and hopefully some pointers as to how to do it correctly.? Thanks for the help.