You'd survive for a while I'm sure.

If you eat fewer calories than you burn, you'll lose weight. For the sole purpose of losing weight it doesn't matter where the calories come from. Mind you, that doesn't mean there won't be other difficulties, such as the fact that it's probably very hard to stay below your caloric limit and not be hungry all the time if you only eat ice cream sandwiches.

Add some veggies to your sandwiches and maybe.

The USRDA exists for a reason.

https://en.wikipedia.org/wiki/Scurvy

Men in the prison study developed the first signs of scurvy about four weeks after starting the vitamin C-free diet