I would pick manual just because thats what I like to drive, preferably.
Boat ramps, hills, daily driving in cities; you just get better at it the more you do it, then you don't even think of it as being out of the ordinary.
For you it makes sense because it would simplify and quicken up the build. And if you're concerned enough about MPG to lower the gear ratio, you would definitely appreciate the mpg savings at the tranny.
If you don't like it you can always swap it to auto; cover up the hole in the floor with a welded piece of metal. No one will ever know it was there, you have carpet right?