Not many people carry a a suitable tow line but as long as the boat being towed has good ground tackle and as long as the water isn't too shallow, there is an alternative that also has some advantages.
On the vessel to be towed, attach a dock line (the longest one you can) to the anchor chain, just above the anchor (or the anchor itself, depending on the anchor type) and connect it to a bridle on the towing vessel. The anchor is then played out until a suitable distance is achieved and the chain/rode is then snubbed off on the towed vessel, as it would be if anchoring.
The weight of the ground tackle helps to keep the tow taught and acts a a shock absorber to reduce snatching and minimize stress to the points of attachment. Just make sure to shorten the tow if necessary as you enter shallower water.