Usdt? I dont agree that is a safe place to hold it :) Personally I will use them and put the rest into SP. Seems to me to be a small error but it might pay itself off later on.
Reason I dont agree with usdt is that it does not have a unified value between exchanges and due to this the market prices gets skewed.
No crypto has the same value throughout exchanges, and there's always chances of arbitraging during volatile periods. Having said this, 1 USDT is backed by 1 USD, therefore the price always ranges between 0.95-1.05 depending on liquidity of the market