I'm pretty sure you can't do that. You would need a welded solution. Having a "dual sport" UTV (meaning you can race it and play in it) is not to difficult to do but your wife is gonna have to climb over stuff to get into it. You should probably come to a UTV race and see the vehicles you will be racing against. These are all purpose built for racing. It might make you rethink what you want to do. Your going to spend a lot to just make your ride race legal and kill a lot of the recreational trail rider comforts to do so.
from the BITD rulebook
All rollcages must be designed and constructed with one front vertical hoop, one rear vertical hoop, two interconnecting top bars, two rear down braces, one diagonal brace and all necessary gussets. The two top interconnecting bars must be placed as far to the outside of the top part of the front and rear hoops as possible. Rear down braces and diagonal brace must angle a minimum of 30 degrees from vertical. At the bottom of the diagonal brace there must be a cross member of the same tubing material and dimensions as the hoop. All rollcage components (hoops, braces, gussets, etc.) must have a minimum of 3-inch clearance from the component to the vehicle occupant’s helmets when occupants are seated in their normal riding positions. All portions of the roll bar or bracing that might come into contact with the vehicle occupant’s helmets must be padded. All portions of the roll bar or bracing that might come into contact with the vehicle occupant’s helmets must be padded. Rollcages must be securely mounted to the frame or body. All intersecting points must be gusseted and braced. Cab or body mounted rollcages must be bolted through the body structure and be attached by use of a minimum two 0.1875-inch thick doubler plates (one on each side of body structure). Bolts and nuts must be at least 0.375-inch-diameter s.a.e. Grade 8 or equivalent aircraft quality. Welding of cab or body mounted rollcages to body structure is strictly prohibited. Rollcage terminal ends must be attached to a frame or body member that will support maximum impact and not shear or allow more than 1.5 inches of movement in the cage terminal end. All vehicles including those with stock steel doors must have at least one side bar on each side of vehicle that will protect occupants from side impact. The side bars must be of the same tubing material and dimensions as the rest of the rollcage. The side bars must be as close to parallel to the ground as possible, be located to provide maximum protection to the occupants, and be securely welded to the front and rear hoops. The location of the sidebars must not cause difficulty in entering or exiting the vehicle. Gussets constructed of 0.125-inch x 3-inch x 3-inch flat-plate or split, formed and welded corner- Definitions and General Information 26 tubing, or tubing-gussets made of the same material and thickness as the rollcage may be used. Gussets must be installed at all major intersections, including diagonal and rear down braces, where single weld fractures can affect occupants’ safety. In the stock classes (8100) on vehicles with rear leaf spring suspension you may add a plate to the front leaf spring outboard mounted hanger if a main roll cage mount is terminated at that point. The plate may only be place in the “V” of the hanger and be welded in place to the hanger only. The plate itself may not attach directly to the frame of the vehicle except for the roll cage attachment bolt that passes through the plate, the roll cage terminal end and the frame. The plate may only be large enough to allow for a good brace for the roll cage mount. Plate design and installation must meet with Best In The Desert Racing Association approval. The rear leaf spring hanger of the rear leaf spring may have a kicker bar attached to the flat horizontal portion of the hanger and extend to the main rollcage down brace. The main rollcage cannot directly mount to the rear hanger. The design of kicker bar must be such that you can unbolt it from the hanger. Kicker design must meet with Best In The Desert Racing Association approval. In the stock classes (8100) you may attach a main roll cage mount to the top of the front spring