basically you need at least 2 heavies. leeanne is generally a guaranteed one, while palffy works decently well as a 2nd heavy (she might even be better than leeanne but have to wait until max stats to check). if you have room in the future, getting bernard up is also a good idea (I needed 4~5 tanks to 2* 100/2 map)
not sure which 50/5 you're referring to, so
https://www.youtube.com/watch?v=GHSpfjEErBU
https://www.youtube.com/watch?v=YbDSIxT8O8g