Your question should be, is there alternative method available of cleaning these windows or can they ONLY be cleaned by ladder access as a last resort. If there is then you should not use ladders. Alternative methods mean those availble on the market to you and NOT what you personally have available. Would suggest you get the details of the hotels own H & S as you will have to abide by their set down rulings and your own industries. The hotels H &S may just have the answer for you. You need to make available a hard copy method statement and risk assessment, which should be readily on offer to the customer, should they require it.