The maps show the wilderness boundary on either side of the Mojave road. What is unclear is how far off the road does the "wilderness" begin. I would imagine that road corridors through wilderness areas would have to be at least 200' wide to allow for some road realignment do to washouts and other issues that would require movement of the road path. If so, then these "gardens" would be outside the wilderness area.
Cam
I run a annual winter trip through there each year. Since we generally have more than 7 vehicles a permit from the NPS is required. I just took another look at my permit for clarification and it states: (Witholding all the section #'s) 30' to either side of unmaintained roads. 100' to either side of the centerline of all maintained roads, "Kelbaker, Cedar Canyone Rd, Black Canyone Rd. The Mojave Rd from what I understand is not maintained so the 30' should apply.
That being said, after reading the entire permit regulations (There are 51 on the permit) it says nothing about leaving any items at the "Mailbox" or the "Penny can" It does state all trash, waste, waste water etc must be packed out. I can see how some may see the frogs, gnomes and trucks might be considered garbage but I really don't. It's one of those quirky things you see that has developed over time in the desert. I have never seen trash or other debris blowing around at the Mailbox.
Our group often has done a little maintenance there like repairing the flag pole Old Glory flys from etc as needed. In the end, I think they will probably take everything away other than the mailbox. People will continue to come by and leave more frogs and the like only to be swept up wash rinse repeat. I'm just a little saddened that something that kids and adults really like to stop and see probably won't be able to do so in the future. I guess for many of us it's just more government over reach because afterall they really do know what's best for us all,..,...,......,..........