I also removed my radiator, though I see you didn't remove yours. I can say that removing it took about 5 minutes and created way more room to work. In addition, by removing the radiator you spare it from potential damage, i.e. leaning on it and breaking the tiny plastic "nipple" from the cross-hose or possibly bumping into it with your ratchet. A new radiator ain't cheap...

I didn't remove my tensioner, just removed the big 19mm bolt on the front, then dropped it about 1/2 an inch which was plenty of room to get a straight shot to that lower front bolt with a 1/4" extension.

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280