I think 5g a day kratom habit shouldn't impact your opium experience much.
That said, kratom does disproportionally raise opioid tolerance relative to its rather mild activity as an opioid (with respect to plain leaf kratom).
But 5g a day is a very low dose, and shouldn't make a big difference if you plan to take a strong dose of opium.
Maybe wait till you are in kratom withdrawal, and then take opium.
How do you plan on taking it? Do you have opium in resin form, or are you using poppy pod tea? Or poppy seed tea?
Whatever you do, don't smoke the opium. While an interesting experience (especially if you are smoking opium you've collected from plants that you've grown), smoking opium is a big waste (unless you have a huge amount of it). Taken orally produces a much more intense and longer lasting high.