Welcome to the forum, from a fellow Sunseeker owner.
RV builders are mainly just assemblers, sort of like home builders. Don't look too hard for an overall model specific manual or schematics because you are very unlikely to find those for most RVs. However you can probably download manuals for your individual components and appliances.
2020 Sunseeker 2440DS on 2019 Ford E-450, Trekker cap, Topaz paint