Brazilian LHR: if I want to leave a patch/strip, can I still do full Brazilian on first treatment to make the patch softer?

By lasering you will discover less hair in the treated areas.  Over time it is possible to get 90+% hair reduction.  If you are looking to reduce hair in 1 area, 1 or 2 Laser Hair Removal treatments should suffice.  I have had male patients who shave their beards 2-3 times a day and have used the laser hair removal system we have at Las Vegas Dermatology (the 755nm Alexandrite & 1064nm Nd:Yag laser) to thin out the hair with a couple treatments.  I've had others who wanted their beards, "Styled in" using the Laser Hair Removal tool to do just that.  Good luck and find a laser institution that can handle any possible complications that may occur- ingrown hairs, burn, infection, and pigment abnormalities to name a few.

Your option is perfectly fine. One or 2 treatments should not completely remove the hair in the area you want to thin. I would shave completely for the first couple and then trim to the desired style after that.