Is a one domestic diversified stock ETF and one diversified bond index fund considered diversified enough? So basically stocks and bonds.

Question:

Is a one domestic diversified stock ETF and one diversified bond index fund considered diversified enough? Any ideas or suggestions based on the context and information below?

Context:

I'm a 25 year-old dual US-CAD citizen who's just getting seriously into investing. To avoid tax complications, although I live in Canada, I shouldn't be investing in any Canadian stocks or bonds. US ones don't have the same complications. I can ONLY invest in Canadian Stocks through my RRSP (Canadian Retirement Savings Plan). I also can't use a TFSA for tax reasons.

I may also get double-taxed when selling Canadian real estate so that's not a viable option unless maybe I buy real estate from the US. I don't need to pay any rent at the moment though and I'm not considering real estate until mid-30s (can just choose areas with low rent until then once I move out).

Additionally, international stocks may be even more complicated tax-wise and be expensive to report so I'm not considering those at the moment. I have no clue about commodities and I think it will be difficult to deal with and track as well. However, I MAY consider them after talking to a CPA and finding out about their tax implications for me.

More Info:

I'm planning on investing into US Vanguard SP&500 ETF (stocks), vanguard total bond market index fund (bonds). I know it's quite aggressive but I'm considering 90% into stocks and 10% into bonds.

I'm aiming to add 5% to bonds though every 5 years. So basically by 60, I'd be at 45% into bonds, and at 65, I'd be at 50% into bonds.