Right off the top it looks like the 'define_method' code is accepting the value for 'Parameters' as a hash ref instead of an array ref so I'm not sure you are going to be keeping the order of the keys to begin with, especially with the latest version of Perl.

That aside, unless you are in a position to rewrite the app (which I would guess is significant in size) to use named parameters instead of positional you have probably come up with the best way to do what you want. The entire problem disappears if you can switch to named params. Plus, you can take advantage of CPAN modules to enforce type checking, etc, like you are currently doing.

Of course, if you can make the change, then go whole-hog and covert to Moose since what you have here looks a lot like someone tried to invent Moose with positional params.