Included Column versus Filtered Index
Yes, modifying all 11 NC indexes to be filtered indexes (CREATE INDEX ... ON ... WHERE DeletedDate IS NULL) would help. This way you get two advantages:


The Query Optimizer will know that any row coming from these indexes already does satisfy your query filters on DeletedDate, so it won't have to lookup the clustered index to double check the DeletedDate
All NC indexes will be 10-15% smaller in size, requiring less memory and fewer IO operations to lookup.


The trade off is that any query that looks after soft deleted rows (and there have to be some query, otherwise why do the rows exist?) will be unable to use these NC indexes.