It would raise the issue of receiving more personal than you have personal quarters for.
IMO, the neatest way to handle it would be to have the game handle a limited pool of volunteers, that you draw from whenever you recruit. Monthly results and specific missions would increase this amount.
About vehicles, the XCOM engine and screens really needs an empty hangar to attach them, so it works better if hangars are naturally more frequent than finding / receiving a ship. I can imagine two different methods :
- The hangar buildings would be item storage and/or manufacturing as well, so that the player naturally builds more.
- The game mod would use ready-made bases that naturally have many hangars (this simulates how the resistance doesn't build from scratch : they take control of areas, or convince other groups to join them)