Can anyone give some advice on how they have been able to do this with loans of 5BTC and up?
Collateral of course makes the most sense, but it is a difficult arrangement, especially for tangible assets.
I would loan BTC on real estate deeds, and possibly other assets.
Any advice would be appreciated!
Your best bet will be either collateral or collateral. If you decide to take alt coins as collateral make sure you get at least 120-150% of the loan worth. When dealing with that much volume of an alt coin there is always the risk of huge swings in value if they default on the loan.
If you are going to go the route with real estate deeds or other physical assets, it's going to be tough to coordinate it unless the person receiving the loan lives close to you. Otherwise it will be more hassle than it's worth from my experience.
Good luck to you