Thanks for the replies!
Upon further research, I found this was enforced in another city/jurisdiction, (wasn't my job, my apprentice told me about this instance).
A little more history: I built unistrut racks to mount on the flat roof (concrete with rubber membrane) and was going to use hollow wall anchors to bolt the bases to the roof...when I had my helper start bolting these to the roof, we found out that the anchors wouldn't set and pulled out!
I finally called the local inspector for the city I was working in and he told me it was okay to mount the disconnect directly to the RTU providing I didn't cover any access panels! (Some people do have common sense after all!)
. Anyway, he didn't have any problem with gas line distances, etc.
As far as supporting the j-boxes, any suggestions?
I thought of using pipe stands (you know, the aluminum ones) and strapping the j-box pipe to them, but this seems more cosmetic than anything, a strong wind would seem to just blow this over.
And further on, I have a big disconnect to mount later on (3phase 150A) and I don't see any available space on the RTU.
Any suggestions would be greatly appreciated, but remember the problem with the roof top. Now if I can sweet talk the roofers so they don't kill me....