Getting ss? LOL how old are you?That's exactly what the SBLOC is. If you have enough of a balance to be doing this in a way that can fund your living, you have enough for a cushion to weather any down years. You could dial back from the most risky stuff but I don't think you should have to scale back from simple funds like SPY or something.
And, if you're getting SS, the loan is paid for. Doing an $80k loan each year costs $2600 in interest. You could either sell some funds each year to pay the loan (after they gain more than the loan interest), or float this as long as you need (I would say, stay under 50% loaned, though to make sure you never get liquidated if the market tanks). Then when you croak, bam – everything gets paid and what's left goes to whatever/whoever you put in your will.
Since i have been doing this as a profession, the date ss will run out of money has been pulled in more than 20 years. Same for reduced benefits.
IF you are planning on ss being a major contributor to your retirement and are under 50, i love your faith but would highly recommend you not listen to me but instead do some homework. Hate to see you "plan" on it as the odds are you will be severely disappointed.