Helping secure work permit via trials?

There is a player(free agent) i REALLY want to sign, but as he is only 18, he can't secure a work permit. Is it possible for me to keep offering him 4 week trials for a period that England will give him a work permit after such a long stay there? I intend to keep giving him 4 week back-to-back trials anyway, until he is given a work permit.

Also, how does the international caps count toward work permit? How many games a year or how? And do U-21 games count too?