I dont mean to call you out but , if they are wood then surely they must be caked with webs even on a monthly cycle , i know my wood jobs do , same sort of surroundings , but then you do use a 6 foot brush with car wash jetting

If you can get away with it then power to you bud , i would not even attempt that with my backpack for fear of scimping to get it done .
Out of interest what do you price that at , just curious ?