For reference... Here is where I have my Garmin Oregon 450T.
The cool thing about this GPS is that it has the capability for 3 wireless sensors.. Temperature, Cadence, and Heart rate. While the heart rate might be useful for a Black Bear pass decent, I don't use it, or have one.

I do however use the Temperature sensor.
https://buy.garmin.com/en-US/US/shop...-11092-30.html

I have the sensor mounted under the lid of my Engel fridge.. That way I can keep track if I'm going to have cold beer at the end of the trail. You will see the temp in the top right corner of the display... Cool 36 degrees :-)

 

in that case the only limit would be gps i guess. everything else could run through a single device. there may even be a solution for gps.

although i agree to use a specialty device when you get improved performance or you want dedicated use.

 

This is the best handsfree I found: Land Rover 04 13 4in1 Bluetooth Handsfree USB iPhone iPod Streaming Audio Kit | eBay
It is only $300 and does everything I need, handsfree, streaming, phone, phone book, USB, speech and iPod. Better than OEM kit. Also docs are at mCAR Multimedia Interface - Land Rover

 

All you need now is a coffee grinder. I would look at my rear view and get distracted by all the stuff around it but I am old fashioned.

 

The ELM324 works with Torque app. on a smartphone. no wires etc.
I am going to incorporate a tablet and Smartphone sometime in the 04. Use the tablet for Navigation/music and the phone for monitoring temps, topo's etc.
I just prefer wireless and mobile. I use the ELM and the Phone for all vehicles.

I am not affiliated with any company I just picked the ELM on ebay and it worked for me,

 

Sh-----t, Ten times more gauges than a Cessna 152 and 50 times more than a D2. You wouldn't want to go there with a hangover.