honestly if you get enough calories you can keep ur mass… strength gains will come but they will be slower than you’re used to.
IMO, keep the strength training for a few months but tone it down to a maintenence level… hell consider it just the time to build up your work capacity.
work your conditioning a lot, that way you can tolerate lifting and muay thai eventually.
After 2-3months of that (maybe less) you can lift again and make decent strength gains and even size gains if you get enough calories… more carbs and protien for every training session you would have that day.
Im lifting, doing MT and BJJ right now, and I can manage it but I built up my work capacity like a mofo.
Only problem i still have to deal with every now and then is tendonitis in my elbows/forearms from striking.
So make sure you
wrap your hands WELL
warm up WELL
maybe use bengay/tiger balm to warm up your joints also
ice after practice if you need to
wear neoprene sleeves where gets sore from training especially when lifting.
this seems counterintuitive, but extra workouts (louie simmons style) will help a ton, especially if you have an office job. Take a strong mini band with you and do a couple hundred tricep pressdowns, and pull throughs, do some skier squats against a wall, shadowbox a few minutes, etc. get those nutrients to ur muscles and helps you from being stiff. But again watch out this could possibly lead to overuse so use sparingly but keep it in mind as an option.
Anyway your goals are entirely possible, just hard to manage and you have to know your body really well. Like K.A. said though, huge benefit is that you won’t gain much adipose tissue at all (if any).