Except for the necessary motions to masturbate, of course.
I only method I can see where these are not entirely mutually exclusive concepts while going solo would be this.
There's probably a way to get such things online or offline; depending on where you live and what you can afford.
Either that or you're going to need someone else to do the restraining, as far as I can see.
Dare to be different... and make a difference.
To boldly go where no one in their right mind has gone before...