I'm still looking for this app! Would be really cool to have. I usually just use the 'cardio' when longboarding, but this is quite unspecified...
Unfortunately this does not work as by recording in "other" does not allow for use with GPS so you will not get your speed, or distance mapped. When I spoke to Garmin on the phone they suggested to start the running activity instead although this would impact running statistics.
Which watch do you have? Odd that you can't have GPS on for that type. In my old 920XT I created two Other types: one with GPS and one without for all those activities that didn't had dedicated types in that watch. Now with my 945 it never occured yet, but when I check my "Other" type, GPS is activated.
when Pushing, I use "SUP - Stand Up Paddling" on my Fenix 3HR :D.
It kind of measures my pushes/strokes too, as I swing my arm when pushing hard. no level changes/downhills though, but living in NL doesn't really matter.
I also use "E-Bike" for Eskate route mapping.