To remove headlight assy, you don't have to remove bumper entirely. Well, it's not much energy saving, but still helps me lots everytime I remove headlight assy.
My friend's site. He has hatch back but it worked on my sedan as well.
http://minkara.carview.co.jp/userid/200156/car/277855/545951/note.aspx
Normally, you need to remove following screws to remove bumper
2 clips and 2 screws on grill.
5( center undercover)+3(front part of mud guard)x2(R&L)=11 tapping screws on undercover and front part of mud guard
and peel front mud guard( 3 bottom screw clips each side) to access bumper side screws.
but with this way, you can omit 5 screws on undercover and hang bumper like 2nd picture in the link.
This will make enough space to remove headlight assy. Make sure you cover the edge of the bumper to prevent scracthing on headlight lens, fender...etc..