I did in my 2015 DX3. I didnít do it for a race trailer but what I did should work for your race trailer. I put a sub panel in right after my transfer-switch and installed a 30 amp breaker with a 100í 30 amp power cord that I use to power another RV while boondocking. I have used this setup on multiple occasion and it has work great.
I wired a outlet into the hitch on the back of my dx3 it has a weather proof cover to cover it when not in use or during rain - I have it wired to my main breaker box and itís on itís own breaker - hope this helps
You wrote, "It have a 50 amp shore power input on the outside of the trailer." Did you mean you have a 50 amp input on your MH? Also how much power do you want to have in your trailer. If only for lights, a fan, or even smaller power tools you could just plug an extension cord into the outside GFCI outlet of your MH.