Bottom line - your D700 or D710 mobile should have TEMP configured as one of the digipeater aliases.
Yes position reporting is perfect for SAR, but what most Hams are not training for is text messaging too. APRS text messaging provides the ability to do AD-HOC comms ANYWHERE and beyond simplex range.
You can extend the range of any APRS HT (for text comms and positions) as far as you want with mobile D700/D710 radios. (I was suprised to see that the FTM-350 does not appear to digipeat?). AD-HOC Rnage extension of packet is far easier than setting up an AD-HOC voice repeater for wilderness coverage.
Yes, a mobile D700/D710 can also serve as a voice cross band repeater, but only one hop. With DIGIPEATING, the range can be extended indefinately by additional mobiles. AND ALL D700/D710 mobile should already be fully configured for always-on digipeating via TEMPn-N, so as long as there are D700's at the event, text messaging should work as far as they travel.
If every D700/710 you know of is not configured this way, why not!??? Who will help make it happen if not you. (I think the D710 digipeater defaults to TEMPn-N enabled.
All SAR teams have to do is use the path TEMP3-3 or so to go three hops back to HQ via ANY availalbe D700/710. Try it next time you are simplex-near a D710...
SAR teams and other Ham response groups should include text messaging (and TEMPn-N mobile digis) as a routine COMMS RANGE EXTENDER in wilderness terrain and practice its use!. See www.aprs.org/TEMPn-N.html