Design it yourself. All the tools you will need are on the Internet. Many installers just take too many shortcuts. It will only be as good as the weakest link. Don't have any weak links you will be good.
The biggest shortcut installers take is insufficient wire size. Many installers use a 3% cart. A little lower gauge wire doesn't increase your costs much. Don't do the 3%, it assumes everything else is perfect.
You should do all the calculations yourself even if you have someone else install it. Do the measuring of distances yourself to verify. Determine where the "stuff" should be mounted.
In my research I wanted red for positive and black for negative in my wire runs. My calculations showed 4g wire had minimal voltage loss but I could only get it in black. 6g had red and black but my voltage loss was to great, for me. 2g had red and black available. I needed 35'. I bought the 2g. Used every bit of it. Everything is in conduit. My voltage losses are around 0.03v.
Do it yourself, grab a son in law or two.
2004 CRV TOAD/1990 WRANGLER TOAD ROCK BUILT