Cross sheeting of jib sheets is common. Once around the leeward winch then trim from the high sides. Only issue is what is in the way and what does the crossed sheet interfere with.
I haven't figured out what you're trying to do with your mainsheet, but a trial run of a line should show you the issues. Perhaps some strategic notches in the coaming will be necessary?
Changes to a boat are funny things. An owner will have a brain fart and do something wacky - then be thrilled with it. Other owners of the same boat will see the change, and maybe 1 in 4 will like it, and only 1 in 10 adopt it. Some owners of other boats will like the idea, but realize it won't work on their boats. Plus, I don't think most owners will modify their boats - that's the way it came from the factory, it must be right.
When I bought my Tartan 30, it was 15 years old. The primary winches couldn't be turned in a full circle, as the winch handles hit the lower life lines. I redid the lower lifelines and fixed the problem. Not the only original defect! Just last fall I found another one - the cockpit bilge pump had been installed upside down. Pump always had taken a few fast strokes to prime - no biggie. Older valves and colder weather brought on a 'no prime' situation. Investigation showed that the pump had been installed so that the flapper valves hung open rather than closed. Reversing the pump and the flapper valves (due to set) restored the pump to good operation.
If what you have isn't working for you, change it!