Read the fine print.
There are quite a few different costs and fees associated with renting a portable trailer, so be sure you read the contract carefully and understand all the charges you're liable for and when they're due. This includes delivery and installation, cleaning and repair charges, and removal fees.

How long can you keep it?
Ask about what happens if you want to extend your lease. Some dealers will charge significant premiums if you want to add a month or two at the end of a multi-year lease. Other include automatic renewal clauses that kick in unless you say otherwise.

Setup counts.
The installation of a portable trailer can have a big impact on your satisfaction: it needs to be level, solidly blocked, and properly skirted. Make sure the setup crew does a good job - and don't hesitate to ask the dealer for adjustments.

Avoid "rent to own."
Just like rent-to-own programs for consumer goods, these programs are usually a bad financial idea. Monthly rents for portable trailer are low enough that you should stick with traditional leases.