I thought I had to have a tailgate step but glad I went with a AMP Research BedStep. Easy to extend and retract with foot. Also can hold onto bed side when entering and exiting and can use with trailer attached.
Sorry just realized you were referring to the tonneau cover. I installed the 4 recommended drains, 2 front and 2 rear, and I have only had very minor leaks after heavy downpours.
I am still satisfied with my purchase. Retraction of the top is not as smooth as I would like but acceptable. Rack is solid! Also added a rack from Harbor Freight that accepts a vinyl roof top bag for storing life jackets, fishing gear, paddles, … that fits under kayaks. Had modify to raise up...
I went with a Syneticusa Retractable Hard Tonneau Cover with Adjustable Rack Kit from Amazon. I have only had installed about 3 months but am very satisfied with quality and price.