I bought the yellow lego-style too....work fine on asphalt/concrete
However, since I have more space since I mounted a 60"L x 12"D x 14"H aluminum "ditty box" on my trailer tongue I have gone back to treated lumber pads... and like others ....did it by repurposing "scrap".
I have 6 - 1in Plywood-T all cut to 8" x 8" plus a few extra cut 4"x4" for leveling campground "picanic tables" or our Coleman cooktop.
I have 4 - 2x6 - T cut to 14" (a length that will slide between tires on our dual axles).
I have 4 - 4x4 - T cut to 10" length
I also retrieved a length of very old 6x10 - T mailbox post that had broken off at ground level - made 4 - 6x10 blocks each 8" tall (and a real bonus cause the aging made these blocks weigh in at only 4-5 oz!)
All these blocks were cut in dimensions to 1) provide sufficient surface area in softer ground and 2) to fit closely together within the "ditty box" without wasting any cubic inches of air space around them....in fact I filled some leftover spaces with 2x6 - T in 10" lengths to allow varying the height under the front jack support......or for use around the camp. I keep a wisk broom with them to brush off dirt as we break camp.
Not a lot of wide variety of terrains for use yet....but looking forward to using recently added 8" tall 6x10 blocks to reduce cranking required at the four corner scissor jacks.
If you like a tiddy looking setup.....bear in mind you can "glue up" scrap blocks of treated lumber with "below water" grade of construction adhesive to make something that "looks good" in use.
So, in summary I'd say I'm old school...the plastic blocks I will use when parked on asphalt or concrete but they just don't "stack up"
to wooden blocks.
BTW WICKED......is it the picture are your rear scissor jacks mounted to the underside of the rear bumper or actually to the frame?
And FWIW....just IMHO...unless there's gravel in that dirt underneath those little bricks.....I could see a good rain leading to them sinking in.....same physics that makes high heels treacherous off the sidewalk.....not enough surface area for the weight resting on them.