First, I would seriously advice not to tinker with your life and uncertified wirings.
There is a reason why authorities restrict connections to thingies like autopilots!
Back, yes, it is possible to convert the GPS data in an iPad and stream that via WLAN or Bluetooth - it is called an iOS2NMEA2IP server, but you will need a receiver for the wireless to convert to a wire based serial interface as well. These wireless-RS232 bridges can be purchased, but they also have not a very good reputation for reliability. So, in the end you have a non-certified GPS in an iPad (point of failure #1), converts signal reception to NMEA (point of failure #2), packs them into IP (point of failure #3), sends via wireless (points of failure #4 and #5), backconverts to wired serial interface (point of failure #6), feed it to a 2-axis autopilot (point of failure #7) and then converts that to what, rate based or attitude based autopiloting (point of failure #8). Are you really considering to value your life over such a thin line?
Cheers for your input; you reaffirm some of my thoughts, specifically that a wireless link is not an acceptable medium for communication of this nature. Hence why I was looking for a (more likely android) solution via a USB>serial output hard wired to the autopilot. This in itself negates points of failure numbers 3,4,5 and 6.
Bearing in mind this is an uncertified aircraft and cannot fly in IMC, I struggle to see how an erroneous NMEA string is going to cause immediate death; sure, it could wander off course; but it's not going to turn the aircraft over, and the worst excuse for CFIT I can conceive of is "the autopilot did it"!
So, do I trust a Trio Pro Pilot autopilot, correctly installed, following a route generated by a GPS chipset uncertified to aviation standards? Sure, I trust it to work well. Would I set it going and take a nap? No.
I have a vacuum DG that has no output other than the obvious one; all the autopilots I have seen for LAA aircraft have required an NMEA input. Without that, it's still able to follow a compass heading from the inbuilt sensor, however the ability to follow a track would be nice, and the ability to follow a pre-programmed route even nicer!