Provide validation markup on a specific field(s) within a loop using serverside recorderror

Hi guys, I'm wondering if there is a way to record an error to a specific
field within a loop and provide css markup to that field. I know this is
really simple to do with a non looping field, just not sure if it's
possible within a loop. Validate="" is not going to be an option in this
case for me do to backend business logic being needed.

Example, A loop of 14 activityCode fields and field 3, 5, 8 have errors. Is
there a way to provide markup to those specific fields? If I do
recordError(activityCode, "my error"); It seems to mark up the last field
in the array.

Any thoughts?