I am looking for a bike rack that fits inside a Van.
I drive Toyota Sienna.
I took out the rear seats and one of the middle seats, so I can put two bikes into the van without removing the wheels.

However, it is kind of jury rigged and was wondering if anyone knew of a rack that would keep the bikes stable without removing any wheels?

You could have a set of rails fabricated and attach two roof trays to them, then put that into the van. You may need to have an attaching system fabricated too, but I don't see this as too difficult. I don't see why two frame attaching trays can't be bolted to the floor if you plan on this to be permniant.

what about those racks that are made for truck beds?

I have a Chrysler van but am guessing that you probably have those retractable hooks that are supposed to allow you to hang clothing. I remove the seats on one side and string a bungy cord from hook to hook. I slide the bike in from the back and make sure the front of the saddle slips over and rests on the bungy. This is like a clothes line and suspends the bike upright. Another bungy around the frame to the seatbelt thingy keeps the bike from moving around. It's simple, low tech and allows me to slip the bike in and out in seconds without taking wheels off.

Park - Like your idea. Will give it a try.
Larue - Truck bed racks. Will look. If I do not need to install it permanently, maybe.
DiselDan - Like your idea, but not sure I understand it completely.
I would not bolt to floor, but could attach to the grips in the floor where the seat.
I cannot envision the other part, however, I get your concept.

I carry either three road bikes or a long wheelbase bent and two road bikes in the
back of my Sienna but I take the front wheels off two of the bikes. The third goes
up against the side of the van and is bungied into place. I got a piece of plywood
about 15 by 30" and put a 2x6 down the middle long ways and used those front fork
grabbers from Performance ($6-10ea) screwed to the board. I use a long bungie cord wrapped around the board hooked into the folded wire hooks behind the folded down rear seats to keep the bikes from sliding forward and carpet runner underneath to protect the rug from drips and debris. Works reasonably well and not hard to roll bikes in and out. Steve

I carry my bike in my GMC SUV on a home made rig. Purchased a front wheel chalk and wheel holder from a bike catalog, Price Point as I recall. Less than $20 for both. Then I bought a 1"X4" about 4ft. long and installed the two items. The bike faces the rear with the front wheel off and the fork locked in the front wheel chalk and the wheel mounted on the wheel holder mounted next to the window. Lower the back single seat and leave the double seat up. Back wheel fits nicely in the single seat area and leaves the rest of the rear for equipment/travel gear.