Rich, I am 6' 1" x 90kg x 74 years of old age and find my Yost Sea Cruiser just fine re stability. And that's after shifting from a Prijon Touryak with at least 100mm (4") more beam and over twice the weight and buckets of stability.
Entry is a tad more difficult with 2 x hip replacements BUT put your butt on the aft deck (I put in 2 aft deck beams spaced a "sit bones" apart) and, has been mentioned above, put your hands on the gunwales to carry your weight and slither in straight-legged into the cockpit. I did not include coaming support brackets in my Yost and have not encountered a problem so far; my coaming just sits on the to of the two frames either end of the cockpit. And here's a tip for an intending builder - make the coaming first before you finally set the frames in place on the strongback to ensure the coaming actually sits on the frames! You would not be the first to find the coaming shape was not perfect and was just a tad too short lengthwise.

Is your Sea Tour a single chine or the multi chine version ? ( i think the latter are a bit less stable initially c.f. the single hard chine version)