You may be able to do as you suggest and remove the bumper with the insert and the shock absorbers still attached to them. Seeing as you'll be replacing the absorbers and the bumper insert with different pieces, you could leave them attached and just get new T55 bolts if yours are done/seized. In all the write-ups I have never seen it documented this way or attempted, but worth a try I'd say.

__________________
Daily Drivers:
- 2008 535i, 320,000km
- 2004 X5 4.4, 01/2004 production, 420,000km
- 1997 328i, 350,000km

Track:
- 1996 328i, track/race car, ~300,000km

Winter:
- 2013 Ski-Doo MXZ X 800 E-TEC, trail can
- 2007 Ski-Doo MXZ Blizzard 800 HO
- 2001 Ski-Doo MXZ 600 w/800 engine, exhaust
- 1978 Ski-Doo Olympique 340 (vintage race sled)
- 1977 Ski-Doo Olympique 340E