Has anyone looked at a strategy of deferring rrsp income - leave it all in situ until 71 yoa.

Use heloc or non-arms length mortgage based on rrsp to extract value of savings (including rrsp) into a high yield pf.

collect say, 80-100k (1.5mm pf at 5.5-6% yield) of dividends until 71. Perhaps write off interest paid on heloc or AL RRSP mortgage through capital gains or rrsp withdrawls.

at 71 start withdrawing from rrsp - perahps sell off the dividend PF to avoid having "too much" income.

I estimate the tax savings at 75% by using dividends, so maybe 20k of less tax per year. 

If you do this for 15 years (defer 20k of taxes) might you be further ahead than pulling out 80-100k from RRSP (~33% tax rate?)?

Was thinking at 71, you're going to pay 40-50% tax rate, could "yolo" into growth investments since gains are subsidized (lost to tax anyways).

I don't see such a strategy employed anywhere - why not?

In the the MoneyReady App you can certainly model both the leveraged scenario with dividends  and compare it to the other scenario where you just withdraw from the RRSP.  The dividend scenario is not guaranteed to work better, it's highly dependent on the factors like your yield and interest rate on the loan (which should be deductible in most cases). The taxes you pay on the dividends are highly dependent on other sources of income, so you also need to condider the timing of CPP and OAS (with its pentential clawbacks). Leveraged scenarios are also inheritently riskier, so that is also something to consider.

Let us know what you find!