I sail a gaff cutter single handed most of the time. You just need a routine with the running backstays. The mast wont fall down as you tack, there's plenty of time as you go through the wind to release one and set up the other. When gybing I haul in the main sheet, release the back stay, gybe, then set up the windward stay and then ease the sheet again. All very leisurely.
I am guessing that your Nicholson 30 is a fractional rig racing type of set up.
The running backstays may be optional being fited to reduce forestay sag. So the importqant thing is to know if they are critical to safety of the mast. Probably not in light winds or in strong winds with small sails. if they are optional then to leave them fitted but not tightened is ok. You could set them up at leasure on a long tack but beware they can cuase trouble if one is set up tight when you jibe or tack and need to ease the main and the running backstay is stopping the sail. Around here most people on even highly tuned racing boats get rid of the running backstays (in some cases modifying the mast staying to support the mast) but here we have tight manouvring and lots of short tacks in a narrow river.
So the answer is yes you could manage running backstays in the ocean but not necesarily in a tight corner. yes highfield levers would be ideal. olewill
Having raced with and without running backstays I would have to say I prefer not to have them.
I recall when the Mazrams started, all had running backstays, the one arrived with a standard set of swept back spreaders and cleaned up the fleet in all conditions over the next 3 months of racing.
It's true that in good conditions when everything is under control tacking is just a matter of routine and timing; ask yourself this, how many times have you been out of control with a standard rig, and what may have been the outcome if you had runners?
Sailing single handed is not for all, but you need to be very mindful of an involuntary jibe and the wrong back stay under tension with a mainsail trying to push it, and the mast further to leeward. Not my idea of fun.