That's not just a problem for you, that's a problem for search technology itself.
Unfortunately, if you optimize your page for one term you automatically de-optimize it for other terms.
Sure, you can have multiple h2 tags and lots of body text -- but you can only have one title tag and you should only have one h1 tag.
You can build links to the page with both keywords as anchor text, but that's doesn't give you the multiplicative advantage of good on-page SEO.
Really, you should have two pages -- one optimized for each keyword. But, of course, that means you have to link build to two pages. This isn't such an issue these days because Google puts so much weight on domain authority. Building links to any page on your site is good for every page on your site.
I once built a whole web site just by changing one word -- across the entire site. I bought a script and changed it from optimizing for a high-volume high-competition term to optimizing for a medium-volume low-competition term.
The web site cost me a domain registration fee and $25 for the script. I think I've probably spent $40 on article marketing for it also. It's made $230.49 in the last year and it just keeps slowly cranking out the revenue with no additional effort on my part. Thats good RoI.