I thought the armor kit effected the center of gravity badly and lead to the vehicle becoming even more role prone that it was originally (Which I don't think was nearly as bad at Hummers). I never drove a Hemmet, but did drive the BIDS version of the Hummer, which had a huge laboratory box on the back and those things were bears.
https://en.wikipedia.org/wiki/Heavy_...Tactical_Truck
I think a lab version of the Hemmet is going to have some issues. The vehicle is a ten ton truck but I think the armor kit only covers the cab, not the payload area. I have seen some gun trucks that have armor on the payload areas but that basically takes up the whole weight of the payload and doesn't leave much for anything else.
In adddition the Hemmet isn't NBC sealed. The HML is all about surviving in a post strike environment. It will certainly have a harder time climbing hills but a lot depends upon the trailer. The HML trailer is designed to house, protect from a nearby nuclear strike and then launch a 30,000 pound ICBM.
With either the Hemmet or the HML the payload will need to be fully custom. I think that a lab doesn't need to be as long or as heavy as the missile trailer was.
YMMV