Hoof Boots for gaited trail horses

I know people that use the "Renegade" hoofboots on their RMH and TWH. They use them for the front feet, going barefoot except in extreme terrain, then use Easy Boot "Epics" on the back, as needed.
I hope to start our trail horses on boots, making the transition from shoes to boots(and barefoot when possible).
My question on fitting:
How critical is the current or recent trim to accurate boot measurement?

The current or recent trim is very important. Keeping your feet a consistant size is a must for boot fit. You will find that regular trimming is a must. I would recommend measuring your horses feet before and after have their feet trimmed. Depending on hoof growth and shape you may find that your horses hooves do/donot change much over the course of a trim cycle. Typically the flatter soled feet that are wider than they are longer will have drastic size changes between trimmings, where as a narrower footed horse wont have much of a change at all.

Eric