I bought those handles from Home Depot in the furniture parts section for about a buck a piece and they are painted metal and I used stainless screws and drilled through the hatch and sealed with Goop. I use it just to turn and pull that darn sticky thing off...which you and everyone else already know...LOL
The anchor line cleats will work too. I didn't think of using them. Both give you leverage and that's all it's for anyways. I wouldn't tie it up using the handles as that hard plastic hatch lid would shatter on a good tug.
On another note I made the spider rig interchangeable. I did not glue it and I can raise and lower the angle of the rods and change out for another rig I have with only 2 rods for more spread. Easy to change and pull off as needed and of course weighs next to nothing. Also added padding to floor to dampen sound when fishing shallow. Pads from Harbor Freight work great.
And of course it's a "motorized" vehicle and I had to register and put on nav LED lights. I added all around green LED lights as well for night fishing and installed switches to handle it all.
Have fun with the handles...they are perfect!