I think getting the desired result by improved security is going to take a long time, given that some airports are in areas where corruption is common and others are in areas which are hard to secure. As such, you have to assume that a potential stowaway will gain access to an aircraft, so exploring means of denying him entry to the wheel wells is a perfectly valid option.
As for being daft and dangerous, many good ideas are triggered by something that is in itself obviously not a good idea but that set someone else thinking. That's why we have brainstorming sessions when creating new concepts, daft and impractical ideas often lead to a workable solution. The initial idea may take three minutes, turning it into a workable solution that achieves an acceptable increase in weight, doesn't compromise safety, isn't too expensive and has a low failure rate, may take months or years. Understanding why an idea is daft is progress towards a solution.
How about a Gurkha armed with a knife and a parachute in each wheel well - he can defend it against incursion and when the doors open for gear retraction he can jump out and hope his parachute opens in time. Then he can catch a taxi (or walk) back to the airport and repeat the process.