Letting people opt out or opt in would destroy the entire point of a jury. It'd turn what needs to be a representative random sample of the population into selection bias.
I think that a better solution would be for small companies, independent contractors, students, etc., to buy into an insurance pool; such that when they are selected for jury duty, they can be fairly compensated.
What we do now bears little relationship to "a representative random sample of the population". We deliberately rule out everybody who has any relevant knowledge or preexisting opinions about anything related to the case or the legal system, thereby making the sample far from random.
(I believe in Jury Nullification - meaning I think the jury has the responsibility to judge whether the law itself is unjust and if so refuse to convict under it - and I object on moral grounds to a fair number of existing laws. As a result of having these views, I have never been able to serve on a jury. I would only be able to serve if I lied to the judge about my beliefs.)
I think that a better solution would be for small companies, independent contractors, students, etc., to buy into an insurance pool; such that when they are selected for jury duty, they can be fairly compensated.