Sounds like part of a very good plan. I think in the long term (over next 15 years say) they need to get a National League team in every region of England plus ideally 1 each in Scotland and Ireland, it would be nice if some become SL clubs, but NL would be much better than what we have now.
As for non-represented English regions we have:
West Midlands
East Midlands
East
South West
South East
Coventry, Nottingham and Hemel would be the best bet for the first three but the last two would be harder.
Therefore I would suggest a round of on the road fixtures (as they had in 1998) with 1 game in each of those 5 regions (rotating round cities there) and 1 each in Ireland and a major French city (other than Perpignan or Toulouse). Though maybe you could rotate a North East game in there as well somehow in place of one of the others some years (probably East as the smallest region there, and the nearest to having a NL club but one which is from probably too small a town to support a SL club, though easily big enough for NL)