Thank you for your question. You have an interesting situation and can understand why you'd want to preserve your precious dahlia tubers! I can't offer you an area of land to rent, but Minnesota has many community gardens which you can use - each one is unique and I'm sure you can find one in your Orono/Wayzata area. Here is a link from the MN State Horticultural Society:

https://northerngardener.org/resource/map-of-community-gardens/

Lake Minnetonka has a very active garden club which may be able to guide you to the appropriate source:

https://lakeminnetonkagardenclub.com/

Wayzata also has a garden club:

https://wayzatagardenclub.org/

Best of luck to finding an area for your tubers and happy gardening!