Laugh if you choose to…
I keep a sleeveless vest and a pair of shorts (only half of a mm thick) behind the seats in my ute. If you have to get it done in the rain, wear one or both of them under your normal uniform. Better than rain over/outer gear which never keeps the water out, is sweaty, heavy and awkward. A light wet suit in the rain makes more sense, I have been doing it since the 1980's, and the thin suits are so much better these days.
EDIT: Long sleeve top if you are stuck on a ride-on, my long sleeve stays at home these days, long sleeves are too hot and restrictive if you are moving around, they are only suitable if you are glued to a seat.
The sleeveless vest rolls/packs down to about the size of a beer/soft-drink can, the shorts are about the same size, the long sleeve top rolls up larger. All 3 fit in the space of about 4 beer cans.