RE: Inside - Outside Temperature
There are a bunch of such setups on the market.  The one I've been using
for about 10 years has the Oregon Scientific name on it but virtually
identical units sell under several names.  In my case I have the inside
unit on the cabinet wall of my Westy and it shows inside temp, outside temp
and the temp in my refrigerator. The refrigerator and outside temps are
picked up with wireless sensors that transmit to the base unit.  The one in
the 'fridge is a simple plastic box, I change the batteries once a year.
The outside temp is a unit that has a long wire on it with the temp sensor
on the end.  I mounted this on the dash to the left of the instrument
console and ran the temp probe down the front side of the door jam and
under the wheel well where it is firmly attached.  There is a LCD readout
on that unit so I can see the outside temp while driving but it transmits
to the base unit in the back so I can see the outside temp while parked.
The base unit has a memory for high and low temps on all channels, great
for checking just how cold it got last night. This setup is about 10 years
old now and newer setups are a little different but will still do the same
job.