Sailrite includes double sticky tape with the kit.
As for mechanical means to hold seams, hems and binding on the inside edge of curves, in order of my preference:
HDX 3/4 in. Mini Spring Clamps (37 cents each from Home Depot)
Binder clips from an office supply store, such as 3/4 wide, 3/8 capacity
Plier-type stapler. Test a few times to determine maximum spacing and also for removal removal from one side of the work might be easier that the other. In any case, be sure to remove to staples to avoid rusty staples after installation
Seam tape, which is sticky on both sides
Seam tape is listed last because seam-tape can gum-up the needle. However, seam-tape seems almost essential for long, internal runs. Not only does seam tape gum-up the needle, it also gums-up scissors. I dedicate a pair of inexpensive scissors for cutting seam tape.
Ways to help mitigate gumming the needle is to and apply narrow seam-tape offset from the line of stitches and/or use a thread lubricator. Another way is to press seams without using heat (heat effects the water resistance of Sunbrella) such as with a Marshalltown 2 solid rubber seam roller.