A very respectable number of rotary crewmen have recently crossed over to pilot and are doing well for themselves BUT with regard to it being a good back door - I would say no way.
First, once you're in you really need there to be no shortage of people to do your job AND do well/be competitive at pilot selection rather than just the latter.
Secondly, they got crossovers because they were high calibre candidates for officer & pilot training and had proved themselves in their previous jobs doing very well cause they enjoyed and WANTED to do it; if you become a WSOp to get in you WILL work very hard, get shafted and overstretched and if its not something you want to do really then you won't 'enjoy' it or do well so you're likely to make yourself into the kind of person who won't pass a commisioning board.
Finally, an overall warning on 'game plans' to get in as pilot. who can win a game which has constantly changing rules?