All depends if you need the car ready for tomorrow, Nick.
If he does, it's not a job I'd relish doing in one evening.
As I said "Depends if TB needs his car pretty much every day" Spend half an hour on a spare trailing arm... when bored - shut the garage door, come in have a pint, do some other jobs go to bed, etc over a period of weeks without stress, worry or a deadline.
Not trying to be contrary Nick, honestly, but how is TB eventually winding up with some some de-rusted, freshly painted trailing arms with brand new backplates, everything with a coat of stonechip paint on, presumably brand new handbrake springs, shims, shoes to boot a 'DIY-Non-professional job' versus looking under your car to see everything as rusty as before, only a brand new backplate which has been sawn in half, then welded back together to fit around the hub/arm assembly?
As you say, different ideas of the definition of faffing about. With
time I'd have a go at the rear bearing, but it's certainly not something I'd attempt in a night. So I'm wilfully admitting my own limitations of expertise and ability here.