My goto rain gear is a garbage bag with holes cut for my head and arms.
That is also part of my goto for -20 wind chills in winter.
Most gas stations sell emergency ponchos for about $2.
A hat is also normal wear, a light one to keep the sun out of my eyes and/or put ice under if hot weather,
or a heavier cap to keep my head warm if cold weather.
Heat is my main problem, so I usually welcome rain.
Normal vaseline use. Duct tape on shoes if expecting heavy downpour.
Dry towels and clothing for after the race.
Good luck. Post a race report