I think your option 3 is probably the most realistic, although I know of folk who have stumped up the £50,000 or so that it takes to get frozen ATPL at a similar age and have been viewed sympathetically by employers and ended up with airline jobs.
The commitment required is considerable and the financial efficacy is marginal.
The instructor route doesn't require the cost of MEP, IR etc. and weekends are when instructors are most in demand. There may not be many openings at the moment, but this is likely to change due to the cyclic nature of the industry.
You could also consider just PPL/FI unremunerated which saves the cost of CPL and Class 1 medicals and will keep you flying regularly