Different units have different roof construction so a "fits all" answer doesn't apply.
I'm 250 # and walk on my Flagstaff with no problem except where the A/C ducts are. You can feel the roof give slightly when you get over one of the ducts that are channeled into the roof.
On a SOB unit I did like Mr. Havercamp and used 2" foam blocks about a foot square.
I made four of them, put under my hands and knees and crawled around.
You could always buy a pair of these...
__________________
2022 Cedar Creek 345IK 5th Wheel•Solar & Inverter•2024 Ford F-Series SCREW•7.3L•4x4•Factory Puck•B&W Companion•TST Tire Monitor w/Repeater•Sinemate 3500w Gen.
F&AM Lodge 358 Somerset, PA - JAFFA Shrine - Altoona, PA
Days Camped ☼ '19=118 ☼ '20=116 ☼ '21=123 ☼ '22=134 ☼ '23=118☼ '24=90