There are a number of factors to take into consideration before adding additional components to the RV.

Weight of the item, and total weight of all hardware required to install the item, will have an influence on the amount of future cargo carrying capacity.  Vehicle weight in total affects tire performance, suspension and balance, as well as overall wear and tear of the RV.  Overloading the vehicle with after market additions will reduce driving performance and usually results in costly repairs.

Before adding any additional items to the RV, or enhancements to systems or components installed in the vehicle, first check with the original product manufacturer to be sure the after market item will not void the current warranty.  Coverage on the after market item lies with the product maker, not the RV manufacturer.  Retain all receipts and contact information for future warranty purposes.  Repairs to after market components may require pre-approval from the product maker and/or be performed at a specified service center.

Determine whether your current on board sources can handle the additional load.  For instance, is the after market item going to require more power than the battery bank can provide?   Adding additional batteries can help increase the source, but keep in mind they will also increase overall weight of the RV.

Know where the item can safely be installed without interference to wires, other existing cables or plumbing pipes.  Be specific when directing service technicians on where you want the item positioned.  Go to the exact location and physically point out your preference, even when it requires accessing the roof.  Installing a satellite dome will revise overall height of the RV.

Be sure the after market item conforms to safety regulations.  For example, when installing furniture, confirm it is properly bolted to the floor and does not impede the flow of traffic to prevent a quick and easy exit from the vehicle.  Putting in a washer/dryer will generally require the additional installation of vented doors.

Many components installed at the factory with maximum airflow to avoid an overheat situation.  Use caution to avoid restricting necessary airflow and causing damage to the system.  Rearranging cupboards and closets to add shelving is generally an easy way to expand storage space, however, modifications in one area may require alterations in another.

When an expensive after market item is installed, add the purchase price to your records for insurance purposes.