I played around with string walking years ago with long target bows. It is a bit more complicated than fixed crawl. Most of the time crawl is used for two or three short range options. If a bow has adjustable limbs it works better, but on a shorter one piece it will throw the limb timing off. If you are having difficulties aiming you do have other options. My first would be to shoot split finger, work on good repeatable form, good arrow flight. Start up close with your good form and good set-up and just shoot, keeping an open mind about all aspects of your shot and what your eyes observe. It is not that difficult to be accurate out to 25 yards, but things can get messed up, mostly by lack of confidence and shooting with inconsistent form. Whether you aim with the arrow or not, your eyes and muscle memory can be trained to 'see' the shot. The second option would be to put a three pin bow sight on your bow, shoot through the sight, not to it. I do not like any method that does not allow a variable bow cant, but sometimes a mechanical aiming process can help. The fixed crawl using the arrow as an aiming point makes for a very fat sight pin.