Believe it or not, you do not need suspenders to be authentic. But they do help to hold up your pants! So, if you have suspenders, here are some tips to help you be comfortable and authentic.
1. Note that suspenders vary because they were not issued by the government leaving the soldier to obtain them from civilian sources resulting in every combination of color and design.
2. I have noticed from examining many original photographs that it is not uncommon to wear your pants with no suspenders at all. If your pants stay up without suspenders, you can forego their use. See the pair on p. 104 TROIANI