Hi JB, I'm glad I saw your post. I grew up in Santa Barbara and I was a regular at all of Santa Barbara's beautiful nude beaches, including More Mesa, Summerland, Cemetary. Rincon and Gaviota.
Bottom Line: The hike from Bowen Ranch to Deep Creek Hot Springs is quite a bit longer than the More Mesa trail. As you know, the More Mesa trail is dirt, but improved with those euctalypus tree steps. The more Mesa trail is very short- probably 5 minutes max from the beach to the top of the cliff even at a very slow pace. The steepness of the More Mesa trail is actually steeper than Deep Creek, which ascends and descends fairly gradually. The only part you or your wife may have trouble with is near the bottom of the trail as you approach the springs -a section (about as steep as More Mesa) with a fairly loose unconsolidated sandy surface with some manmade natural steps cut into the hillside.
In reality, the trail will probably be fine for you guys as long as you take your time, do some rest breaks, and enjoy the gorgeous vistas and "aesthetic viewsheds" (eat your hearts out Environmental document writers, I just made that up!) of Deep Creek. Enjoy! REgards, Paul P.