The Blue Trike (check it out in the garage or my album) was a Trike Shop Rounabout. Gloria had them put a foot accelerator on instead of the hand throttle. It turned out just like a car - gas pedal right next to the brake. Didn't need to move the brake to the left side. Wasn't that big of a thing to do, or that much of an expense. (Well, compared to possible hand/wrist surgery or therapy) Can't see it in the pictures because The Blue Trike has a lower fairing boot.
If it is a matter your hand going numb holding the grip tight,try a product called the "Crampbuster" Lets you use the palm of your hand to throttle instead of gripping the bar. They are around $10.
CrampBuster - The Original Motorcycle Cruise Control
As for your last question - Only you can really tell, but my wife would rather have me spend the money on fast motorcycles than fast women.