Negligible RRSP room and lower income isn't enough of an answer. If income is not projected to rise substantially over the next 5 years, saving RRSP room is useless, check the math on growth of the refund vs. bigger later returns. The refund from the first tax bracket, when included into the RRSP, will Grow fast enough (typically) to offset saving the RRSP room for the future (saving it for 10 years will put the person behind, again check the math). If Income is projected to rise in the near future, then wait. Using RRSP refunds at the early stages can snowball NW, early investing often beats delaying.
I understand the arguments for delaying RRSP contributions. They are predicated on having available TFSA room. In this case, the OP has maxed TFSA so the argument is; should the money go towards RRSP or taxable? A smaller RRSP account in Early Retirement can also be tax free, for example if you have $100,000 and withdraw 5% a year, you can still pull a boat load from the taxable account and some from the TFSA to get a decent income of $20-25k without paying taxes.
To get $100k in an RRSP with income under $40k requires $80k of personal contributions (ignoring growth and assuming 25% marginal rate). That's $20k free money, tax free, if you FIRE with lower spending.
On a personal level, my wife never made over $45/year, when we withdraw from her RRSP I expect it to be tax free, but we also got a few thousand in refunds over the years so that was sweet. A small RRSP account is not in the same category as a typical retiree with $500k in RRSP. Ignore RRSP if you want, but in my case we ended up richer, even with a lower income.
https://cdn.canadiancouchpotato.com/wp-content/uploads/2019/03/CCP-Model-Portfolios-ETFs-2018.pdfUsing the aggressive model, 10% bonds, that would be $13,500 in bonds for the RRSP (under $11k in personal contributions, right there we shoot NW up 2% and we haven't done anything). If there is more room, or usefulness in contributing more, put US and Worldwide ETF in there next. The TFSA should hold Non-CDN ETF, that one is easy. The taxable account is the catch all then. In a taxable account, there are some better ETF's to buy for non-CDN ETF, its a pretty rare thing so it's hard to find good articles about it.
If you ultimately conclude RRSP is still a bad fit for you, then its TFSA holds US/worldwide and taxable holds an american ETF, some US/worldwide and then some bonds. You balance your entire portfolio across all account types, NOT in each account type.
If you base your investing choices based on taxes, you will under perform. If you base your allocation based on taxes, you will succeed. Notice how I'm only talking about where to allocate the money, the TFSA/RRSP/taxable discussion is just about how to divide the pot of gold.