I don't have the extended overhang but had to lower my EZ-Pass a little lower on the windshield with the standard overhang to make it reliable It was not being detected about a third of the time, when it was up towards the top of the windshield.
I have extended cabover with regular cab with no problem. I don't have a satellite radio or GPS. Thinking of GPS so borrowed my mother's, put it on my dash and drove around for about 15 minutes and never lost satellite signal. I do love the extra sun vizor the cabover provides.
All of my TC's have been ext. cabover and all my trucks have been reg. cabs. I have a shorty radio ant. and mount my EZ pass on the license plate. My GPS sits on the dash and no problems with signal.
I don't have satelite radio.
"04" CHEV 2500HD DURAMAX DIESEL REG CAB SRW
2010 NORTHERN-LITE 10-2 SPECIAL EDITION
15 YR OLD BORDER COLLIE (LADY)(no longer with us 6/23/11)