If it is going to be temporary, you could go a LOT cheaper with something similar to a MICO (ZF) brake lock. There are some with a tiny lever instead of a button. That would look hysterical in a Seven. Keep in mind it only locks in the pressure you have already applied to the hydraulic system.
Some centuries ago, I was a UPS delivery boy and had a wonderful package car with a MICO brake. As I came to a stop, I could apply the MICO and be standing in the door when the van actually stopped. Back when UPS drivers were reputed to run.
RYANSTAR Hydraulic Handbrake Adjustable Ebrake Long Lever Handle Fit for Drift Track Rally Racing Master Cylinder 0.75, E Brake Racing Emergency Brake Vertical Position Ergonomic Handle & Anti-Slip
4.1 out of 5 stars 113
$41.99$41.99