Just to elaborate on what i was suggesting above, you could do the following format.
For example:
F1's for 2008 all gain automatic entry into BRCA 2009 1/10th National Series (So there's your first 40 drivers for 2 & 4wd)
Regionals could start earlier, i.e March and be run as a 3 round series with 2 to count towards National qualifying scores.
1 Regional run on the same date in each region say 1st March, 1st April and 1st May (again for example)!
I don't know how many regions there are, but you'd have to allow for a Percentage based on the amount of attendee's as it wouldn't be fair to say Top 10 from each region when some regions only get 8 people turn up! So say the top 10% qualify to compete at the Nationals.
I think Nationals should be limited to 100 people per class, allowing for more run time on the day (which seems to be an issue with a lot of people, even with 2 practise rounds it seems you don't get enough track time) - So how about 3 x 4min practise sessions followed by 4 rounds of qualifying and finals to continue as they are now with 3 Legged A finals.
When it comes to Regionals i think it would work if F2's are automatically seeded in their region to go into the top heats, followed by F3's, F4's and so on.
This allows for similar racing to Nationals and you could introduce a more National like format with timed practise, 4 rounds of qualifying and then finals.
This could allow you to then run say just 4 Nationals to allow room for Euro's and Worlds, and they could be run June, July, Aug and Sept.
I know this probably isn't ideal but it's just an idea :-)
I just think the only way you're going to notice any changes are to dramatically shake up the current system and accept that it needs to change!
If it doesn't work, it's easy enough to go back to normal for the following year so why not give it a go one year
There could also be an incentive for F1's to compete at Regionals as practise for the upcoming nat's by seeding them for the Top heats at Nat's - so for instance the Top F1 from each region automatically goes into Top heat (Heat 10) and so on..... I'm sure there would be a way to get the F1's racing at regionals anyway but this was just another idea i had.