Is this a continuous, full length of the rail, or just spaced out hand holds?
If it is full length I would rip the step on the table saw and then use the router with an edge guide the length of the rail and a template bushing to make the cut with the bit you choose.
If it is hand holds spaced out, then a plywood template and router bushing along with a straight bit , then the round over bit and a 3/8" larger template cutout. The top round over (1") can be a bearing guided 1/2" BB Bit.
Just a suggestion.
Thanks for the thoughts. I have not decided yet whether it is full length or just at the hand holds. Yes, the hand holds are spaced out, as in the photo, just not as long (12").
I would really like a full length step. I would like to rip the step as you suggets, but I think I do not want to attempt it with the table saw that I have (Sawstop Jobsite). I love the saw, mostly, and am simply thrilled to have a table saw. That said, I am seeing more reasons all the time why I should "make" the room for a larger saw. With the router table and the saw, a comparable amount of floor space is occupied as would a larger Sawstop with router extension table. Both of the latter would be much better than what I'm working with now.
The existing fence, while OK for a lot of uses, is not really up for ripping a 2x8x8ft edgewise. At least not without a lot of help, in form of fence extensions, both longitudinal and vertical and I would want another person to help with the heavy lifting and holding during the ripping. I do not have another person to help with this.
So, I'm not sure yet what I would do to put the step in at each hand hold, except to say that it will involve templates and bushings, etc., as you suggest.
"...the bit you choose..." is the operative question, which is the only point to my initial question/post. I believe the Ovolo bit is what I want.
My dilemma is where to find/get one. I need to go to a major city to get some vitals from Costco. Woodcraft is having a sale event Sat. Both are located 1) three hours east in Boise, ID or 2) 6 hours west in Portland, OR. I have a gathering of friends that I could attend in the Portland area, but was not going to go because I really didn't want to drive 6 hrs twice in three days. But, I may break down and do the trip to Portland. Better chances of finding the Ovolo bit I want there also.
So, the beat goes on...