I can imagine a better collective for both:
an intrusion (rats) of Clinton signs
a skulk (skunks) of Clinton signs
a plague (doves) of clinton signs
a murder (crows) of Clinton signs
A flamboyance (flamingos) of Trump signs
A tower (Giraffes) of Trump signs
OK, Mr. Dunphy( 8th grade English teacher) how did I do?
A business (ferrets) of Trump signs.