An obvious concern would be the combination of a brief and rapid rise in blood pressure (which is likely to occur during an intense experience), plus a blood thinner, leading to an arterial rupture and uncontrolled bleed. We are talking about hemorrhagic stroke. You would need an underlying weakness in an arterial wall to begin with.
To quantify the increased risk of a bleed due to being on enoxaparin, while smoking dmt, is impossible. You would have to be unlucky. But common sense should prevail. Personally I would wait until the enoxaparin is ceased. That way you will feel more at ease going into the experience.
Can't comment on the seizures. It's listed as a possible side effect, but I've never seen one occur in those on enoxaparin.