A second tier comp is an interesting idea...but I don't see it being viable having teams from the WAFL in it....having teams travel from and to WA would send teams broke, it is just too far....the air costs would be too high.
Rather, I see something like a South Eastern league (ie SEAFL), consisting of 14/16 teams from the SANFL, standalone VFL teams and maybe 2 teams from Tas (Hobart and Launceston). Perhaps other towns like Mt Gambier, Wodonga and Mildura etc could join down the track, depending on how successful it is. With this idea, I see most resistance coming from the SANFL...I don't see them going for it, as they have way too much to lose.
If it was the SEAFL as you suggest the clubs still have to fly between Melbourne and Adelaide which wouldn't be that much less expensive than Perth, especially with an airline sponsor/arrangement. My original idea was the 8 WA sides + 8/9 SA sides + say 3 Vic sides + Tas possibly (since they won't get an AFL licence for many years to come I think under the current expansion talk coming from Demetriou). So with 20 sides, 19 rounds playing each other once, the WA and SA sides only play about 4/5 interstate games. Of course this would be closer to 8/9 for Vic clubs and 9/10 for Tassie which is a disadvantage. If successful I think the travel expenses could be born by the competition management out of sponsorship/media rights - assuming the competition is viable enough to attract media interest.
Maybe I need to do some reading up on the VFL/VFA as I really don't know the first thing about this comp to offer input. If you were to identify VFL/VFA clubs that would be interested who would they be and what is the size of their supporter base? Remember all interstate games will only have attendance by the local crowd so that would in general terms halve the attendance and therefore gate revenue. Also what is the current size of their club budgets?
On the issue of the SANFL resistance. The thought popped into my head today that maybe the SANFL dispensing with the Crows and Port licences will be a good move. Why? Because they will be able to make future decisions being fully independent of AFL ties and will have to stand on their own two feet. So they might be more open to proposals in the future.