Hi sporter, I'm not able to answer your exact question, but perhaps can give some input... I have a Harley Fat Boy with the Champion kit --- pretty much similar in size and appearance to the VTX with a kit. I am very petite, just 5' tall and about 110# and am doing fine without reverse. It is something I can add to this trike at any time, but as yet have not had the need. Put it in neutral and the trike rolls easily. Where there is a hill, I just make sure to position myself where I can roll back downhill out of my parking spot or I back into it so I can ride straight out.
Unless you have a bigger physical limitation than being very small, you shouldn't have any problem.