We sail on jib only sometimes. Ours is a fractional rig with no backstay -- shroud chainplates are a foot aft of the tabernacle. But givent this boat is rigged for a 240 sqft spinnaker, I reckon it can handle a 70 sqft jib okay.
Sailing upwind is difficult with headsail only; and to come about, you really have to work up enuf speed to get your nose thru the wind. Once you do, it's easy -- just leave the jib backsheeted a few seconds and you'll fall off nicely. May cause lee helm, which can put more wind in your sail than you want. OTOH, jibing on headsail only is stress-free -- no boom crashing over. Just keep your lazy sheet taut so the jib doesn't wrap around the forestay.
We reached home last weekend in 20+ knots on jib only. Our harbor was almost DDW, and we feared 3' swells on our stern could lead to accidental jibes. So we left the mainsail in the cuddy & flew the jib. It kept the nose out of the waves and pointed downwind, held speeds down to manageable levels, reduced our rolling moment, and carried us 7 miles in just over an hour.