You are my height and I agree this is going to be a bit difficult. And initially sliding a boat works less well on wood racks than metal ones… Plus getting the nose high enough for the top rack… and your support for flipping it upright to take it down, since you are talking about a boat with rigging and stuff that can catch on the wood.
Sparky’s idea would work if you had an anchor point higher up, but you may be able to get partway there without it. This is a flyer, see if you think it’d work.
Position a reliable sturdy thing nearby that will give you 8 to 12 inches of added height. Position the boat so one end is clear the end of the rack, the other end more inside.
Get a block and tackle, say one like this (https://www.northerntool.com/shop/tools/product_200668083_200668083?cm_mmc=Google-pla&utm_source=Google_PLA&utm_medium=Material%20Handling%20>%20Hoists,%20Lifts%20%2B%20Cranes&utm_campaign=Grip&utm_content=55267&utm_source=google_PPC&utm_medium=Materials+Handling+-+SC&utm_campaign=&utm_content=&mkwid=s&pcrid=39129660716&mtype=&devicetype=c&storeId=6970&langId=-1&type=search&gclid=CjwKCAjw8_nXBRAiEiwAXWe2yakelO2FVM6_CRQr03tJ2n8PSWMZpTQtmf78mAH79Si53sCq2JSnfxoCF1YQAvD_BwE) and hook it to a loop one around one end of the upper rack. In a few inches since those ends are open.
Get the more inside end of the boat under it (probably the bow) and lift using the block and tackle so it is hanging a bit under one side of the rack. Tie off that line so the block and tackle is carrying the weight.
Lift the other end of the boat over the other side of the rack using the reliable sturdy standing thing. Weight should not be an issue since the block and tackle is holding up the other end.
Move the reliable sturdy standing thing under the end of the boat being held by the block and tackle, get the boat weight on you as you release the rope from the block and tackle that you tied off. Lift that end up and get it over the rack. Slide forward as needed to get more centered. Again,weight is reduced since the stern is now supported.
Flip upside down from one end as needed, or use a cockpit cover and straps. Probably don’t need to unclip from the block and tackle until this is all done, but not sure.
Again, maybe not. But for a fairly cheap investment, and at our height the sturdy standing thing is needed for car topping as well, in your shoes I’d try this.