This is a pretty simple, although time-consuming project.
1. The sofa should disassemble into two or more parts for removal.
2. Residential recliners are fine. In my experience, LazyBoys tend to be pretty bulky so check around. We purchased two nice, leather, electric recliners from Macys for $600+ each.
3. Make sure the measurements of the new recliners are appropriate. Key measurements are width, front to back in both sitting and reclining positions. A "wall-hugger" may be your best bet. Base measurements are critical, mine overhang the front of my slide by about 1.5" so I screwed a piece of aluminum angle bracket to the front of my slide. You'll be measuring for both getting it in the door and for putting it in place.
Anchoring the recliners to your slide can be challenging. I made a bracket out of two pieces of aluminum angle attached to form a squared off "Z" shape. I through bolted this to the slide floor using stainless "T" nuts on the bottom of the slide. This bracket catches the back of the base so as to hold it to the floor, while the front of the base is bolted to the angle brackets I screwed to the front edge of the slide.
Others have attached the recliners to an oversized plywood base which is then attached to the slide.
The difficulties in securing the recliners is related to 1) Lack of accessibility once in place, 2) Most slides don't have a thick plywood floor and are foam cored so holding power is limited. A lot will depend on your particular slide and recliner.
2002 Itasca Suncruiser 35U