Great post.
A race will have impact on your immediate performance and recovery following a race. If you are fatigued and I'll that will exacerbate the effect of a race. You must calculate if that matters and how much. You can probably run a race at peak performance without fever, proper rest, and proper ability to breathe.
Modern theories on vo2 max say you don't lose fitness significantly until you have 2 weeks of training backlog. Take this into account. You could bank the rest and reduce your recovery if you haven't been down 2 weeks by skipping your taper run. It likely won't affect your performance.
My anecdotal experience is that my window for inactivity causing fitness loss gets smaller and smaller as I get older. I would take my advice with a grain of 'how old amI'
Disclaimer: Former competitive runner at 5k, 20 marathons and countless small races completed. One 50k completed no competitively. 25 years of running under the beslt. Max weekly mileage 75. Currently 25-40 for this marathon in July. Age: 37. Largest challenge: weight management and the summer fucking heat.