Chevrolet Blazer / GMC Jimmy Owners Manuals | JustGiveMeTheDamnManual.com
You can download a manual for your Blazer at the link above.
If your Blazer is equipped with the correct transfer case, you can push the 2H and 4L buttons simultaneously for 10 seconds. A red light will come on and now your vehicle will roll away even if it's in 'Park' so use your parking brake aka emergency brake before you take your foot off the service brakes.
Putting your transmission in park or neutral has no effect on the transfer case neutral.
Your motor-home and/or it's trailer hitch might not be able to handle the weight of a toad.
IRV2 has a bunch of detailed information on Itasca/Winnebago coaches. Go here
Winnebago Industries Owner's Forum - iRV2 Forums
and check out the first 7 line items marked "sticky".