To note: The same size lines that feed the 'outside shower' feed the sinks and the tub/shower combo in my unit. The inside shower does a fine job with adequate water and pressure. I believe the issue MAY be in the little plastic dispensing head with the on/off lever for the 'outside shower.'
2012 Fun Finder XT 276 Toy Hauler & Harley Davidson Ultra Classic with Condor wheel chock
2014 Dodge Ram 2500 AT 4X4 Crew Cab 6.4 L Hemi, 373 gears, tow package, Rambox option, Revolver X2 tonneau cover, Equal-I-zer anti-sway hitch.