ASEAN nations do have a very competitive AFF suzuki cup which lasts one month - November to December. Their Leagues have a Break during that period.
I do not think they will be interested in SAFF cup because how many breaks their Clubs will take. FIFA Friendly dates are fine, a Tournament like SAFF Championship takes away 20 days from any Domestic calendar.
Best Bet would be inviting one Guest Team from Africa - Sao Tome and Principe or Cape Verde but they will come without their Europe based players
Only dud teams that struggle to get international matches will be interested. The likes of Brunei, Chinese Taipei etc. They won't necessarily increase the quality of the tournament either. Indian Ocean teams like Seychelles, Mauritius, Comoros etc. may be interesting too, but SAFF egos wouldn't want to risk an outsider winning the competition.
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