You can keep a running total of grades and not make it public for students. You can also consider something like a Guttman chart to track your students to outcomes. This allows for visualisation on which students are progressing and where the likely ZPD of your cohort. Providing a grade generally signals that the work is over for this unit and we can move on.
‘too many of my students are borderline failing and need to know where they stand’
The feedback can direct them to where they stand. It should address the goals of the task, how they went, and where they need to go. No grade is necessary as the feedback should indicate if the student is able to achieve the goal and whether they need to readdress the topic (or whether an intervention is necessary) or continue up the continuum.
I am getting my math teams (Grade 7–10) to complete assessment matrices (rubrics) for each richer task (inquiry projects) and long answer questions to provide moderation, transparency, and a clear understanding for what the continuum looks like. These are grade less as they are not used as grading tools per se. We want to use them to provide a clearer understanding of the goals of the task, how the student went, and where they stand on the continuum.
Each test and every assessment is an opportunity for teaching and learning, see Patrick Griffin’s book ‘Assessment for Teaching’. This can include re-testing, but it can also include things like: peer feedback, verbal descriptions of why a formula or computation works, small group discussions about different solutions, peer mentoring, targeted tutorial groups based on specific skills and topics, class discussions on how this topic connects with others they completed, the possibilities are endless!