Anyway, since it is hard to get a suitable enclosure for the LCD display, I just epoxy-ed the exposed parts & traces on the LCD and 3M-ed it to my car's dashboard..
Update 1: It seems lowering the audio setting on PR1 pin/Kenwood data port does increase the number of packets decoded by Tracker2. The default setting was at 9, I reduced it to 6 before and now to 4. Probably it was over-deviation that causes the problem? I've no idea really but will monitor if this is the case.