i think you can say "I don't recommend this" only if you are sure that the packing method can not be done you can use recommended because you know that method is not good option but if you are not sure about it. The option is suggest

suggest is stronger

To suggest something is to put forward an idea or solution. To recommend something is to support it strongly based on previous knowledge or experience. If there is more than one possible idea or solution you would recommend the idea or solution that is the better of the options available . If your client believes he has a method that works but you disagree you can say I suggest you don't do that because..... OR I recommend you don't do that because.