How to avoid Proof Of Concept (mud wrestling)

Proof of Concept (POC) , blueprint or even scripted demos are time and resources consuming both for our customer and our presales team. And worse than that , the POC usually end in a software features battlefield war that means in the fun slang of some of my company's colleagues "to be involved in the bad mud wrestling" where everything can happen including the loss of the deal even though we have got the best feature product. Of course a POC can be valuable if you have got with your prospect a "why not you agreement" whereby your competitors are out of the picture, that means your customer get you in their building and is spending the time with your product and your company that he is not spending with another vendor...
But in other case, POC driven by the customer and the consultancy company that is supposed to help them to make a choice ( the later the better...) and where our competitors are involved too is a bad situation for everybody (except for the consultant company in charge of the choice)

I think there are creative ways of avoiding long RPF answer and long POC cycles explaining they will save money and time by choosing more rapidly ( of course it won't work every time but these some tips are worth it to use) Bellow some ideas I have got :

• Explain for instance to your customer that starting the project 6 month earlier will save him 1 € million (let's say) and go on telling you customer "if we can show you two similar companies who had faced the same problem you do, could you shorten your sales cycle"
• Ask you customer what are their 10 main critical business process in their company and make an outstanding demo that show the additional value of your software for each process. Then tell your customer why is it worth it to waste additional time resources ands money as you have already proved your value.
• Give to your customer a free limited trial/workshop approach in which you install your product in the customer premises for a fixed period in order to address in some meeting their main business goals and process requirement. Of course this approach is also time consuming but you make generally your competitor out of the battlefield.

what about you and your tips and trick in order to avoid long sales cycles with exhausting Proof Of Concept ? tell me I am looking forward to listen your piece of advices and recommendations !