The grease/food waste came from the kitchen sink but it can take years for it to build up enough to clog.

Eventually building a second source of income for myself semi passively to supplement my current job.  

Currently in college and have been looking at wholesaling for a while learning through YouTube and other sources.

If the mobile home has a propane tank or oil tank for heating, it can be problematic because tenants may not be able to afford to fill up and use other types of heat sources.

The source from whom he was arranging 15k is not able to fund/lend him, so our realtor has suggested my friend to take 15k from me and repay me in monthly installments which will keep the partnership 50-50.

As long as you have a source to build up more capital for the next purchase I would say you have chose a good way to get started. 

We feel we have exceeded our investment potential through friends and family and would like to start searching for other sources of funding such are touching base with funds, family offices or sophisticated investors.

Considering your income source is a key factor one needs to understand and take into account when looking to get a loan... 

Good cashflowing properties can still be found you just may have to get creative or find a different way to source properties.

However, be sure the source of your info is good.