Meh. If it's stressing you out that much, just play middle D every time it comes up. I promise you not one single audience member will care.
A friend of mine plays with several Nashville baby acts. Some of them play bro country songs that are all way low. All if their bass players play a standard tuned P bass. Nobody leaves the venue saying "Man, that band would have been great had the bass player brought a 5 string!!!!"
Seriously, work around it in standard tuning. Nobody cares.
(I say this as someone who plays 5 string almost exclusively.)