2 bad options
Robert,If you want to get creative, you could fairly straightforwardly route one or more of the lines to the base of mast, through a block (or double or triple block, as needed), thence to a deck organizer, continuing aft, terminating in a cleat of some sort. Basically, the way the halyards/uphaul are rigged, but take the new lines to the other side of the coachroof.However, there would be several disincentives, IMHO:1) You'd have to purchase longer replacement lines to make the runs.2) You'd have to reeve the longer lines through the boom, over the sheeves & out the grab cleat. Not impossibly difficult, but a major PIA. The PO of our 23.5 never realized the 3rd routing through the boom was for the topping lift (for that matter, others don't either or use it for a 2nd reef anyway). All he had was a messenger line. When I went to reeve the topping lift, I lost the cursed messenger line. I got it reeved eventually, but the mast end internal sheeve was a b_tch to deal with.3) Somehow you'd have to remove or neutralize the existing grab cleats in the boom or they would quite likely engage whenever you wanted to ease the lines.4) You'd add a bunch of potential toe crunching trip hazards to a fairly important traffic area.5) You'd have several pieces of hardware (block, organizer, cleat) to purchase.6) You'd have to install the hardware, including backing plates possibly. This obstacle could be the biggest.All in all, I'm not sure what you'd gain would be worth the effort and other drawbacks.I guess you could try to rig something on the underside of the boom, at least far enough aft that you could reach the end of the line(s) more easily (you probably wouldn't come further aft than where the main sheet attaches). Perhaps just lead it straight back to a fairlead v-cleat. It wouldn't be the best solution. You'd have the end of the line hanging down. You'd still probably need to run longer lines & have to deal with catching on the old grab cleats. And you'd have a cleat(s) hanging off the bottom of the boom on which to hit your noggin!The link is to a Ronstan fairlead v-cleat.