Every sports photographer on the planet has for decades simply screwed in a monopod into the 3/8th inch socket in the lens foot. This is a perfectly sound solution if all one is going to do is to walk about a paddock or pitch with a long lens over your shoulder.
These days many of us fit replacement feet with are arca-swiss compatible (rather than lens plates) and this allows such lenses to be quickly, easily and safely used on compatible gimbals and heads fitted to tripod and monopods.
Many heads have clamps with safety pins which "prevent" the foot from coming off of the head until the clamp is fully opened. This allows the foot to slide a bit and then are stopped. These fittings are a really good idea.
I have to remind those who use QR socket fittings (being those primarily designed for use with slings for carrying rifles/guns) that these ARE not designed for delicate camera gear and can relatively easily release, particularly under dynamic loading (like when a camera is dropped).
I therefore DO NOT use QR socket fittings to carry any of my gear. I replaced these QR sockets with an Acratech Quick Clamp and I have moved to using fittings with Aratech QR lever clamps (not QR sockets).
I use the RRS tilting monopod head with leaver clamps on each of my monopods AND have never had an issue with any of the heaviest of my gear. Most of these I have owned for a very long time.
As alternatives to my gimbal or videohead, I am also using an Acratech Panoramic Head with Locking Lever QR Clamp 1167 together with an Acratech Levelling Base Large 74mm,on a tripod or ground pod or panning plate. AND I use
Acratech Swift Clamp on my Sun Sniper and Black Rapid straps.
All can hold my body weight and dynamic loads without releasing.