I like the idea used in the 2nd video. Just drop it in and use it. 2 boxes, and 2 rails. Simple adjusters.
Since I am going to use my Harbor Freight Hand Planer, I want to show my thought process.
I am going to use a slide system similar to the one used in the second video...on the boat build "Talley Ho.
I think it is important to have the planer set into the track system so the bottom is parallel to the track when used. The front of my planer has a hole horizontally from side to side, for a guide that I can use a 3/8" rod to support the front of the plane. The rear has no hole, so I removed the rear sole to see how much support there was. Not Much. I made a Hard maple block that is inserted internally to support the plastic body of the plane. The block fits inside the body and I needed to drill a 3/8" hole at the same height so the plane bottom will set parallel when dropped into the track box.
To match the location with the height of the front guide hole, I used a drill bit to mark a scrap of maple as shown in the photo. This became a guide for drilling (from each side) through the body so the hole for the rear support is at the same height as the front guide hole. The rear hole aligned perfectly this way (drilling from each side).
I think this will work well, but since I am going out of town...I have to delay further work on this idea for about 10 days.
My planer is a 3-1/4"...and I see Wen makes a cheap 4-1/2" planer for about $65.00.