I had the solar installed the first time, after I saw how it was done I realized it was not "that" difficult.
The last time I used the "Z" brackets & flat mounted them (this is on an RV). Putty under the brackets, screwed then to the roof, Dicor self leveling sealant around the mount pads & over the screw heads.
Deciding where the batteries are going, where the solar controller is going to be mounted & how to route the wires took the serious thinking.
When I put solar on my '86 Ford van I mounted the batteries & controller inside towards the back (pass side) to balance my weight in the drivers seat (probably didn't make any difference).
For the first few months I did not have the panel mounted, I moved the panel around outside. I made 2 connectors (mc4 to male extension cord end & another with the female end. You NEED to pay attention to make sure that (+) on the panel connected to (+) on the controller). One went on the panel & the other was at the mppt controller, I used my extension cord between them. The measured voltage drop thru the extension cord was only one tenth of a volt.
I leaned the panel against the corner of my van, one end for in the morning & the other end for in the afternoon. I moved the panel before I went to sleep so it would start charging with the first light of the morning. The cord that connected to the controller fit under my closed rear door. This set up worked well for me while I was camped in the Quartzsite area that winter.