Interesting thread but anyone who had the cash to own/operate a LJ would surely go down the conventional route of distance learning ATPLs then do a ME CPL IR?
Trying to go the PPL route is almost more work and as said would raise eyebrows with insurance companies. You'd need the HPA groundschool which not that many places offer. Then the IR groundschool which is 7 exams. So the groundschool requirements are really only a few months less work than doing the ATPLs anyway.
Flying training - you'd need the MEP rating, then a fair whack of MEP time I'd suggest, then do a ME IR - 55 hours and then the TR.
All in all, the difference between a PPL qualified on the LJ and a fATPL holder is really only a chunk of groundschool and a 15 hour CPL course. Given the costs involved, small beer!