The only problem I have with racial, gender, and social status restrictions on voting is that progressive and cultural marxist politics could easily undermine these rules. Furthermore it will encourage suffrage movements and play on the vile sympathies of "equality."
In order to get around this it is ideal that the right to vote is granted by civil service of some form. The minimum should be 2 years of hard labor for the state. Rebuilding roads, rebuilding infrastructure, managing state sponsored events etc. The alternative requirement would be 4 years of soft labor. Meaning after an adult completes his/her higher education he/she can apply for a federal assignment where the government believes he/she will be most useful. Upon completion of this the citizen will be permanently labelled as a "Good Samaritan" and will receive higher citizenship status.
What will happen is that some women and some minorities will get the right to vote, but the overwhelming majority of the electorate would be white males who recognize the value of service. Furthermore these service years will be ingrained by default to military service so in the electorate there will be an extreme right wing bias.
Thus if any suffrage movements comes along their argument won't play on the emotional rhetoric of equality, but simply disenfranchisement. To which the opponents of the suffrage movements would say "If citizens feel disenfranchised they can work to earn the right to vote equally and freely with the full support of the federal government."
However the foreseeable problems with that is the possibility of some bleeding heart senators passing a law loosening the civil service required to earn the right to vote. In which case enlisting in the military, becoming a police officer, a fireman, or a general civil servant of significant importance should be an iron prerequisite. This is just a suggestion though, and I lean towards the Good Samaritan approach mixed with this.
This then leaves another problem of taxes, in which many citizens would revolt under the claim "taxation without representation." In which case I believe the lower house of congress should remain completely democratic as they have the power to allocate funds. This should quell any dissent about taxes.
So the solution is:
A bicameral legislature with the upper body represented by civil servants/Good Samaritans.
A lower body represented by tax payers. *not supported by welfare or have committed a federal crime
An executive branch yet again elected by civil servants/Good Samaritans.
Though all of this would be in vain without a considerable control of the media. However this almost always results in state corruption. Therefore I believe an independent government entity should be created, a fourth branch, in which the leader is democratically elected by the entire population of adults over 30. Their role will be to actively investigate the government for inconsistencies, corruption, and inefficiency. They will control all national news and coordinate with local independently owned news companies on serious domestic events. Foreign events will be met with same unbiased coverage regardless of perceived geo-political panic it may generate. In a government in which the right to vote is earned it is critical that the power bestowed by the electorate isn't abused. Their job is to tell the truth, responsibly give unbiased information to the public, and expose liars in the republic.
The leaders of this 4th branch will also receive protection from a force independent from the military but selected from it.