@_act_ is right, people here would prefer the monthly payments rather than using an escrow, not to mention that there's not really a lot of reputable escrows nowadays, you can't trust anyone with large amounts of bitcoins anymore, even if you don't want to believe and believe that there's still something good in the human heart, it's still not a plausible way to do that kind of thing with escrows anymore. Remember the blankcode incident or the Charity that they did, the escrow wasn't doing it right and the funds were sort of embezzled and misappropriated to God knows. Even if you make the campaign managers on board with your idea, the campaign participants would be hesitant to follow through with that plan.
In the other side of the idea, majority of the campaign managers also offer escrow services. So, if the idea is workable, it therefore means that the managers will dual as managers and also escrow managers which will reduce the risk of embezzlement as you have pointed out.
If it is difficult to use Bitcoin on a weekly basis, it is better to stop promoting Bitcoin as a cryptocurrency. The fees are currently high, but there will come times when you can broadcast your transaction for less than 10 sat/vByte and then it will be possible to accumulate all UTXOs into larger future inputs.
It is obvious that bitcoin is failing fulfil her promise of low transaction fees. And I am afraid the good old days of 10 sat/vByte might be gone forever.