Mutual Fund vs ETF (SWPPX vs SPY) [Trailing Stop]

I am very new to investing so I'll share my personal experience.

Last year I opened and contributed to my ROTH IRA.

I went with Charles Schwab for my platform.

I invested the contribution into SWPPX.

Great returns this year, almost no fees (.003% maintenance, no cost to buy/load/sell) and paid a nice dividend in December.

As I continued to learn more this year, I wanted to put in place an order called a "Trailing Stop Loss"

Investopedia - Trailing Stop

That is when I learned some of the drawbacks of mutual funds, as you can't place trailing stop or stop losses on these types of investments.

I am currently considering switching to an ETF for 2018 so I can put a trailing stop loss in place, but haven't sat down to look at how much more I would have paid in fees for the "peace of mind" from the trailing stop loss.

Opinions from the Money Board? Should I keep my SWPPX Mutual Fund? Switch to something like SPY and put a trailing stop-loss in place?

I am:
Under 30
No Debt
~$17000 in a ROTH IRA
I put about $1200 a month in savings after my expenses.
I do not own a home / have a mortgage.