You might consider a hot spot device such as some of the newer phones or like I am using, a Comcast xFininity MiFi router that is about the size of a pack of cigaretts. Other telcoes offer the same Novatel router. This is a 4G connection to your server and 5 wireless devices which can access files on each other, even a shared Filemaker databse. There are several cell phones that act as hotspots.
A remote Filemaker server will not respond as quickly as a local Filemaker Pro file over Wi-Fi so carrying the three items may be worthwhile. If you have a desktop computer with wifi you can have that act as a server for the iPads.
You can also carry 5 iPads and let 5 people play with your applicaiton to prove your point. Pointing out that upto 9 iPads can log into one $250 copy of Filemaker Pro might land a few sales too.
The question of functioning is not just the one you asked which is yes, Filemaker Go will run well on the iPad, the vital question is how well you design the file to meet the design parameters of Filemaker Go.