Thank you for this question.  The absentee ballots were sent out in the formation of the road association long time ago. We have a very large road association (about 75 members). Later, we changed the by laws for in person and proxy votes only. 

When we have a situation of more than 2 people wanting to be a president (wishful thinking) we do secret ballots. The procedures are: When an owner say has 2 develop lots (one vote per developed lot is listed in our by laws) and comes in with 2 proxies, that person is given a voting card with a total of 4 votes written on the card (the registration list checks off the proxy and person's address). When there's a need for a secret ballot, that person will write the name of the president he/she wants, place it in a hat and the votes are tallied up by 2 people (2) to determine who won. If it's a tie, a coin is flipped. In other situations a voting member can call out that they request a secret ballot for voting on a particular topic after the debate is concluded and people are ready for the question/the vote. There is a more complicated situation when it comes to a conflict of interest, but I digress. 

Bottom line, a secret ballot is just that, SECRET. The registration list  indicates who attended the meeting and who was a proxy member. The tally workers are only counting number of votes without any names. The secretary records in the minutes all present and proxy owners names. The total of votes are recorded (NOT who voted for whom). I personally take pride is knowing a secret is a secret thereby I do appreciate your question. 

Since you allow absentee ballots, you could enclose a ballot separate from the signed form, so that you could verify the sender, but only the person receiving the votes would know the voting preferences. If the ballot was on colored or otherwise unique paper, it might make if more complicated to "fake it" if that is a concern. The ballots could then be pooled and counted separately from the filed absentee ballot documentation. You would track who voted, but not how. Given the comment above, it seems like trust in the vote counting itself can be an issue, competing with the desire of members to vote in secret.