Not rare ^^ - let's be specific -
* there are long range missions - THREE general types
1- LR smuggling - take X over to Y: has been nerfed, payout still fairly good, but mission availability fairly rare - avg payouts I see now are 3-6M range; always in format of go from outpost outside the bubble towards mission destinations in the bubble
2- LR transport - legal goods, take X over to Y: not been nerfed, is frequent, always available - not the whole board, but lots of em usually on the board - format the same as above, always from outpost outside the bubble towards destinations in the bubble. Can stack as many of these as you can carry in ship cargo - there is dump cargo cheese but I personally think that's not my cup of tea so will stop at that
3 - LR courier - zero cargo space, same as normal courier jobs but 10-40x the normal payout - nowhere near as good LR transport but pays 100k-600k is range I've seen as Tycoon trade rank
My post about relative earnings that is purely personal to me, not saying valid for anyone else is here -
https://forums.frontier.co.uk/showthread.php?t=198001
Simple 3 step process if you are ok with Fed/Yong ri side of boggle is
1. goto Sothis or Robigo - roughly 350 LY'ish outside the bubble
2. use a cheap ship, LY config Asp with 72T is what I use - add (1) 8T fuel tank - with 28+ LY range but still fully combat configured, lets you fight off interdictions, plus tank means you stop exactly 1 time to refill with fuel scoop. Other option just splurge and get 5A fuel scoop, ditch the fuel tank, and dip and scoop most the way back
3. Can reload mission board if you want, not my thing although in honesty I do occasionally reload once or twice if the board is very lean on transport and heavy on charity missions - the time to drop cargo off is long enough as it is, I don't enjoy doing any one thing for that many hours. At sothis or robigo, I usually don't load up full 72T cargo, maybe 50-60 tons by taking all missions, maybe reload once max, then take 1 courier mission max but usually those are not worth time to land
suggestion - take and pay for every charity mission on those boards so you rank up friendly then allied with the sothis and robigo minor factions. Will help get the bigger paying missions, although tbh, trade rank is what seems to be biggest boost - no xp with lower rank but at tycoon you get the #s I quoted in my post.