The simple answer is YES, you can modify the frame of a Towable RV. The only issue is that cost will be driven by complexity.
Your idea to split the load front and rear is good for weight distribution and to decrease the heft of either modification.
The front end mods will be much more complex with the frame/tongue junction being moved, plus the lights, brakes, propane line, and battery mount and power run.
Our last pop-top was lengthened in the front to allow a quad to be carried...it was great and several mfgts have since copied the idea. The pop-top had a square frame that connected to the tongue and was modified by just adding an extension and deck to the original frame...pretty simple.
To modify a Travel Trailer, I guess you will want to design a stretch to the ladder frame (front and rear) and move the tongue forward...shouldn't be too complex if you have the right materials and tools.
Best luck and hope you post results if you do it.
Kim and Steve, Mustang LCDR (Ret), '07 Damon Outlaw #1193
I have seen gross intolerance shown in support of tolerance, Samuel Coleridge
WE LOVE OUR OUTLAW RV