In my opinion, you do not need guaranteed stops. I have never used them or never will.
If you want or need to trade with large positions with Forex, I reckon you have the wrong strategy and just like to gamble with high risk.
Here's an example. Last week I was trading a few pairs. My best two pairs were GBPNZD and EURNZD. I was attempting to build a basket of 4-5 trades in a each position. The risk was mainly only in my first entry which is normally around 20% of my total position goal. Both of these were posted last week.
Trade 1 was just 0.1 Lot size and in EURNZD I managed to get a full basket of 5 trades. So between both pairs, I had 8 trades at a small size of around 0.1 each ( a few at the end were larger ).
My pip count with the two pairs ended up around 1400 over a week period.
My profit was over $2,000 for those trades which is more than enough to pay yourself a wage.
I reckon most Forex traders trading with a much larger trade size would have profited a lot less than I did.