I think everyone does there own thing for cable management some boxes are to small
Even the large galaxy dimension doesn't have everything in the right place
Although installers will fit your kit , it's not there problem if it doesn't work or doesn't do everything you expected
Most buy there own kit to make it cheaper, but you won't get cheap support after its in , and reading what your saying seems you going to DIY it sooner or later
I don't fit hik
It's it's DIY the above can be recommended by any dealer of hikvision
Otherwise get a new installer but expect to pay more for it he may be able to get you something better
If you can afford it get a dual nic NVR that will solve any bandwidth issues mostly
An great points here , good to look into for matching a monitor