On this trailer the power cable opening was in the center of where the hatch went. This was a 16 SD I installed a twist lock connector just forward of the hatch. The cable came into the shell under the rear SD seat.

Tempress Hatch 13" tall 17" long. to outside of frame. The hatch has an O ring seal and can be installed with door up or down. There are two latches no locks. You can order a lock from Tempress but shipping is high. The door can be removed from the frame during the install. The hatch calls for #14 screws but hard to find in stainless, Just drill out the mounting holes to 1/4" and use 1/4" stainless mounting hardware. The template and mounting instructions call for 1/2" bit drill for the corner radius but it takes a 1" hole saw to make the corners for the opening.

The magnets are used to define your mounting area.

The 1" x 1/8" x 18" stock is used to shim out the bottom of the hatch due to the curve of the shell.

Some trailers have the power plug where the hatch will be installed others have the city water inlet. They will have to be relocated which ever configuration.

This is a fairly tight fit so measure three times and cut once.

This is a fairly easy install and 90% of the work is done from the outside.

Do this mod at your own risk. I'm just going over what I did.

Note FWIW: Pictures are from two hatch installs one std. and one DX S-16.

On the outside attach magnets to your four inside magnets. Take masking tape and run it on the upper side of the of the upper magnets and lower side of the lower magnets. Measure between the front upper and lower magnets and same for the rear. Divide the measurement by 2 to find and mark the center between the front and rear magnets upper and lower magnets. Run the upper edge of a piece of masking tape between these two center points. Now measure your center mark in ref. to the belly band and Scamp lettering and adjust as needed.

Now find the vert. center of your template and line up with your center ref. line Check your front to rear template position by using your cable hole as a ref. for in and outside clearances. Once satisfied with location and mounting screw locations mark the outline and four corner hole centers on the trailer.

Hatch

Pop the door off the hatch frame. Drill all the mounting holes to 1/4" if using 1/4" hardware. Take your 1/8"x1" shim strip and clamp to the bottom edge of the frame. Drill the four mounting holes and mark and cut the radius end corners. The metal shim will be used to shim out the bottom edge of the frame. On the inside if the trailer pull back the rat fur and refletix back about 1".

Dry fit and and drill your frame mounting holes. Remove the frame and install butyl tape (2 times around due to width.) Now on the bottom install  the 1" screws and metal shim strip to the frame. Once aligned remove the screws and add another layer of butyl tape over the shim strip and reinsert screws. Now double up some butyl tape and taper the butyl tape to build up the tape on the ends to allow for the lower shim.

Place the frame in the opening and install the screws. 4 bottom screws 1"  all others 3/4". Install fender washers and nylock nuts. After tight take plastic putty knife and cut away excess butyl tape. Reinstall door to frame. After a day or so retrim butyl tape clean up and seal edges if you wish.