So the 'trouble and strife' is on the back of the bike and the 'tin lid' is in the chair?
IMHO, leading link front ends are for those who want to ride hard and you can get away without one.
Having said that, there may be an increase in safety in having that extra stability and that's important when it's for the wife and kid. I am content with my home made outfit because no-one gets in the chair except Bella the red dog. Anna rides on the back of the bike when she is here. That's the use it gets...apart from carting my bags, fishing gear and bottles of plonk on trips.
Some things, like the adaptor for the final drive and rim, are not easy to come by in a second hand sense. It took me 2 years to find one and that was by sheer coincidence.
To be honest, I think it will cost you less money to buy an already set up outfit like the one Rossco showed us, than to buy yourself a sidecar then have it set up with the earles forks and rear rim etc. Make that bloke a sesnsible offer and then sell your new K bike or keep it as a solo.
My 2 zsloty worth.