No you dont need to use the rubber. The small amount of water that may get under the shield wont do anything and there is no concern with water into the fairing it will drain, its not water tight.
2011 FLTRX, 103 Power Pak, Stage 1 with Power Vision and V & H Power Duals, SE A/C, Cee Bailey TRSSC 15", Progressive 940 rear,Mono Tubes Front, C & C Fastback Seat and some extras in black here and there
2005 Annv FLSTFI, Stage II 95 kit, lowered 2" - SOLD
2004 Road King Custom - SOLD
2004 Sportster 1200 r, Stage 1 - SOLD