Yes. Our rental system is 100% open source and you are free to modify it as you wish. If you hire a developer look for a Magento developer. Magento is PHP / MySQL based. We have a small programming guide available, and it should be made very clear to your developer not to modify directly the rental system source code, rather to use a local module so that if you want to upgrade your rental system later your custom changes will not be overwritten. Magento is very developer friendly in this regard and it’s possible to do modifications and keep them seperate.