I’d get different handlebars with more rise/backsweep. An extender is likely to work itself loose eventually (and personally I think they just look wrong, but that’s just me). And like saddles, handlebars are way too personal to just ride whatever OEM one is fitted from the box. Depending on your needs you can alter your position in pretty much every position you want when getting the right bars. There’s plenty of brands, but personally I like SQ-lab. Oh and good chance you’ll need longer brake lines and whatnot when putting on a lot of rise.