Yes, you
could go as short as 65" on a maple selfbow. But why would you? Why do you want to go that short? The longer, the more forgiving, more so for a beginner. You could glue down some linen/silk fabric or rawhide. I'd avoid that ff*ugly drywall tape, though. If you make the limbs 2" wide at the fade, and taper them to ½" nocks at one third from the handle, you'll have a solid maple selfbow at 65" or so (designed for a 28" drawlength), IF the stiff handle is short and the tiler is good. A good board of maple is harder to find than a good board of oak. I can see grain run offs in your red oak bow, especially in the upper fade (bottom pic). For a selfbow, you want zero of those run offs.
Good job on that red oak first bow, though! Keeping the first one hold together and with a decent drawweight, is quite an achievement. But where's the full draw picture?