I was going to suggest using riser bars, as is quite normal on today's bikes. Only drawback is the possible need for longer cabling, especially as such bars tend to be wider.

And making sure that you aren't height-constrained by a too-short seatpost!

Also seconding the suggestion to consider shorter cranks if your legs are feeling overworked or if your saddle height seems like a difficult adjustment decision.

I don't think that the saddle needs to be moved rearward. Possibly/likely raised, but today's mtb's all have much steeper seat tube angles than your bike.

Your stem has minimal forward extension length, so I think there is hope for achieving a good and proper fit (this coming from a similarly-proportioned 5'9" rider having a relatively long inseam).