Personally, choosing a light mage would be my last choice. I don't like the idea of shield of heaven at all, it seems very boring and easy-mode hiding behind a shield that is based on how much MA you have. Not only that, but speaking in general terms, in my opinion soul masters are better for PvE. They have a huge range of AoEs, and they do have a fair amount of single target skills as well. Fairly short cast times and easy to use skills. Light mages have long cast times.
As for the funds, you shouldn't need much funding for a soul master. Being as you don't PvP, blessings shouldn't be a very big factor, so you won't need to worry about making them strong.
..I should be sleeping but once again I can't :l