Also.. gang nail plates ain't the prettiest things; perhaps cladding the trusses with hardwood would be a better look (and a painstaking task)
Dark or plain matt paint and dim lighting will hide the ugly.
I know a place with a great hall, the old dark oak roof timbers were practically unseen as it was high and the windows and lighting were lower.
Only when concealed uplighting was fitted could the magnificent hammer beam construction be appreciated.
In your case, don't illuminate the roof.