Prevention is better than cure. Wear some sensible shoes or boots, i.e. oil resistant soles, anti slip type even for WFP as decking, etc can be slippery to walk on especially carrying an extended WF pole.
If customers can't be bother to unlock gates, remove padlocks, etc, especially if they know you are calling then just clean what's accessible and charge them a higher percentage in proportion to what you've actually cleaned and call it the set up / inconvenience price and inform your customer that's what they'll be charged everytime access is denied for a pre-arranged visit. It's not worth the hassle of trying to climb over gates, walls, etc as an accident is waiting to happen.
Brett, I hope you are feeling better now. I feel for you sincerely.