I think rather than going through the trouble of calking your shower nozzle purchasing an Oxygenic Fury shower head solves the pressure problem. The one I installed recently is unbelievably good but it also has a number of spray settings. Check out this site https://www.canadiantire.ca/en/pdp/oxygenics-fury-rv-shower-head-brushed-nickel-0409701p.html

I do like the shower curtain hack and will most likely use it.