The trader's performance means nothing for the security of this loan for the lender. Assuming you are going to invest it, and the investment goes well - what security or guarantee is there that the lender will receive anything back from you? For these kind of loans you would be required to provide collateral, or it is unlikely that you will get it filled.

More likely, it might be possible to explain to someone exactly what to do with the money/deposit and make a deal for future earnings. For example, they deposit the .05BTC themselves and when the investment grows you receive 20% (or whatever) of the profit. This way their money would be more safe on one front, you could earn the money for your own deposit and everybody feels better about the whole thing. Although, even this would be questionable since the trader seems to be your buddy.